Introduction

Infertility is a widespread issue that affects individuals and society on a global scale, leading to various psychological pressures for those experiencing it. Infertility is defined as failure to achieve pregnancy after at least one period of unprotected sexual intercourse regularly for 12 months or more (1). Infertility can negatively affect infertile couples' lives, such as married life. These problems in couples can increase marital conflict, leading to extramarital affairs and divorce (2). Marriage is one of the most exciting and stressful events in the life of anyone in which problems appear over time, and the love and affection between couples and the level of satisfaction in their lives decrease. Marital burnout is considered a significant consequence of these problems, contributing to emotional detachment within the relationship and, resulting in numerous challenges for the couple's children and extended family members. It arises from a discrepancy between the reality they face and couple's expectations, and its severity depends on the couple's compatibility and beliefs (3). Since marital burnout leads to a decrease in love and affection and an increase in hostile behaviors, it can lead to marital dissatisfaction and agitate the family's foundation (4). Several factors lead to marital burnout among couples; some of these factors include social relationship problems, more loneliness, less life satisfaction, and an inability to enjoy relations. Moreover, when couples feel relentless physical fatigue and believe that the issues will remain unresolved forever, they will experience marital burnout, which eventually leads to bitter family disputes (5). Researchers have identified several psychological problems experienced by individuals dealing with infertility, including impulsive behaviors and scattered anger, feelings of worthlessness and inadequacy, anxiety regarding sexual attraction, feelings of rejection, and challenges within marital relationships and sexual orientation (6).

In this regard, one of the factors that can cause marital problems is irritability and uncontrolled anger. Irritability of physiological responses to stimuli as well as pathological hypersensitivity or abnormal sensitivities is a feeling of intense anger, frustration, or fatigue (7).  Irritability is a mood disorder associated with risk factors for depressive disorders and anxiety (8). The fight-or-flight response in the brain causes the irritants to lose stress hormones and lead to adverse reactions (9); thus, irritability is thought of as a milder form of anger, so the criteria for irritability also have several cases that are similar to those related to actions of anger and aggression (10). According to the research of Mikaeili et al. (2023) (11), communication aggression has played an essential role in the marital disorder. The research of Hammett et al. (2021) (12) showed the effect of partner violence on perceived marital satisfaction. Research by Sandberg et al. (2018) (13) also revealed that perceived relationship aggression is associated with reduced sexual satisfaction for both oneself and one's partner. Namdarpour and Bolghan-Abadi. (2019) (14) demonstrated that aggression, communication patterns, and sexual satisfaction are predictors of marital adjustment.

One of the mechanisms that can mediate this relationship is repetitive negative thoughts. Repetitive thoughts are defined as the processes of careful, and repetitive thinking about one's self, world and others, which are at the heart of a number of models of adaptation and incompatibility. Anxiety, rumination, residual cognition, emotional and cognitive processing, review, meditation, and problem-solving are examples of these thoughts (15). According to Beck, just one stressful event for couples is enough to give a negative score to the spouse's desire for a relationship. According to the cognitive model, thinking affects all cognitive functions on behaviors and mental states. In other words, automatic negative thoughts are related to fear, avoidance, and the severity of symptoms (5). Negative thoughts are usually unconstructive, which perpetuate the harmful effects of stressors. In other words, they increase depression in people (16). The research results conducted by Falahati and Mohammadi (5) revealed that the dimensions of automatic negative thoughts could positively and significantly predict marital burnout. Research by Gumus and Kislak. (2019) (17) demonstrated that the level of repetitive thoughts affects mental health and marital adjustment in married people. Identifying essential variables in this domain can offer valuable insights for infertile women, fertility specialists, family counselors, and psychologists. This, enables the implement of interventions aimed at preserving and enhancing couples' relationship. Considering the aforementioned statements, it is anticipated that irritability may impact the marital relationships of infertile women by influencing repetitive negative thoughts. Consequently, the overarching objective of this study was to investigate the design and testing of a causal model of marital burnout through irritability with the mediating role of negative repetitive thoughts in infertile women. The conceptual model of the present study is shown in Figure 1.

Materials and Methods

The present study, based on the nature and method, is classified as a model testing correlational design with an applied purpose.

The statistical population of this study consisted of all women with primary and secondary infertility who were referred to infertility centers and obstetrics and gynecology medical centers in Ardabil, Iran in 2022. A minimum sample size of 200 individuals is recommended for structural equation modeling by previous studies (18). In this study, due to the limitations in accessing infertile women in Ardabil, 420 of them were selected by convenience sampling method and participated in the research through an online questionnaire.

 In terms of inclusion criteria, the study included women with primary and secondary infertility who had been unable to achieve a successful pregnancy after 12 months or more of the appropriate time with unprotected intercourse. The age range for participants was set between 25 and 50 years, and a minimum literacy level was required. Participants were also required to be free from underlying diseases. The exclusion criteria included unwillingness to cooperate and distortion of the questionnaire. To ensure adherence to ethical guidelines in medical research, the study followed common codes of ethics, including codes 13, 14, and 2 (benefits from the findings for the advancement of human knowledge), code 20 (coordination of research with religious and cultural standards), and codes 1, 3, and 24 (satisfaction of subjects and his legal representative) have been observed in the present study.

Data for this study were collected using the Pines (1996) Marital Burnout Questionnaire, Poorafroz et al. (2020) Irritability Questionnaire, and McEvoy et al. (2010) Repetitive Thoughts Questionnaire.

The Marital Burnout Questionnaire was developed by Pines in 1996. The questionnaire has 20 items that include three main components of physical fatigue (e.g., feeling tired, lethargic, and having sleep disorders), emotional exhaustion (feeling depressed, hopeless, trapped), and mental exhaustion (such as feeling worthless, frustration, and anger towards the spouse). All of these are answered on a seven-point scale. Level 1 indicates the lack of experience of the desired phrase, and level 7 indicates the high experience of the desired phrase. Its response range is of the Likert type (from 1 = never to 7 = always) (19).The lowest score in this questionnaire is 20, and the highest score is 140. A higher score indicates a greater sense of marital boredom. The test-retest reliability coefficient was 0.89 for a one-month period, 0.76 for a two-month period, and 0.66 for a four-month period.

alpha coefficient, ranging from 0.91 to 0.93 (19). In Iran, Gohari et al. (2015)  (20) examined this questionnaire on 240 people, and Cronbach's alpha coefficient was 0.86. In the present study, the reliability of Cronbach's alpha method was estimated to be 0.85.

Irritability Questionnaire This questionnaire was designed and standardized by Poorafrooz et al. (21), which finally changed the number of questions from 70 items to 44 items with ten factors. In the present study, the form of 44 multiple-choice questions has been used. The questionnaire has 44 questions with a Likert of 5 degrees from strongly disagree = zero to strongly disagree = 4. Irritability in this study includes the concepts of anxiety (6 questions), high arousal (3 questions), hostility (4 questions), haste (3 questions), inconsistency (7 questions), lack of perseverance (4 questions), lack of concentration (5 questions), acting out (5 questions), dissatisfaction (4 questions) and impatience (3 questions). In order to evaluate the degree of desirability and internal consistency of the expressions, first descriptive indicators, correlation coefficients of each expression with the total score and Cronbach's alpha coefficients in case of deleting each expression were examined. Phrases with minimal or less confusing factor load were omitted, all expressions related to depressive factor were omitted, and the analysis was performed again. Finally, a simple factor structure was obtained that with 10 factors with a specific value higher than one could explain 70.28% of the variance. Cronbach's alpha coefficients ranged from 0.68 to 0.92, indicating that all subscales were stable.

Negative Repetitive Thoughts Questionnaire McEvoy et al. (2010) designed and developed this questionnaire in 2010 to measure negative repetitive thoughts. This scale has 31 questions. To calculate the predictive validity of this tool, Beck Depression Inventory and Beck Anxiety Inventory were used, and the correlation coefficients were 0.42 and 0.38, respectively (22). The reliability of the Persian version of this tool was also calculated by Khaleghi et al. (2011) (23) through Cronbach's alpha coefficient and was reported to be 0.89. The correlation of this instrument with BDI (0.52) and BAI (0.53) was used to calculate the predictor validity.

 After obtaining the necessary licenses from University of Mohaghegh Ardabili, infertility centers and obstetrics and gynecology medical centers in Ardabil were referred. With the coordination of the questionnaires, the questionnaires were distributed among infertile women. Due to the fact that the convenience sampling method was used in this study, the link remained active for three weeks after the online questionnaire link was distributed, and during this period, 420 questionnaires were provided to researchers by eliminating incomplete cases. The questionnaires included necessary explanations such as the purpose of the research and how to answer the questions. It was emphasized that participation in this research was voluntary.

Eventually, upon collecting the questionnaires, the researchers conducted raw data analysis using descriptive statistical tools such as mean, standard deviation, variance, and Pearson correlation test in SPSS software version 25. Lisrel software version 8.8 was also used for Structural equation modeling. The significance level for the tests was considered as 0.05.

Results

A total of 420 women diagnosed with primary (282 people, 67%) and secondary infertility (138 people, 33%) in Ardabil with a mean age of 35.89±5.45, were in the age range of 25 to 49 years. The majority of the participants, comprising 46.19% (194 people) reported living together for 5 to 10 years, 53.81% (226 people) stated they had experienced infertility under five years, 32.86% (138 people) held a bachelor's degree and 67.51% (217 people) described their economic status as average.

Table 1 presents the mean and standard deviation, the variables of marital burnout, irritability, and repetitive negative thoughts. Also, Shapiro-Wilk statistics of research variables are not significant. Thus, the distribution of the variables of marital burnout, irritability, and repetitive negative thoughts is normal. (P>0.05).

Based on the findings of the correlation matrix (Table 2), significant positive relationships were observed between marital burnout with irritability (P <0.01; r = 0.51) and negative repetitive thoughts (P <0.01; r = 0.56), at a 99% level.

The final modified model, as shown in Figure 3, utilized structural equation modeling to investigate the direct and indirect impacts of irritability and repetitive negative thoughts on marital burnout in infertile women.
The fit indices of the research model are as follows: Comparative Fit Index (CFI) 0.93, 
Normalized Fit Index (NFI) 0.94, Goodness of Fit Index (GFI) 0.91, Chi-square to Freedom degree 2 .70, and root mean square error index (RMSEA) is 0.064.
According to the results obtained, it can be concluded that the research model is approved in terms of significance and fit indicators.
According to Table 4, the direct effect of irritability variables and negative repetitive thoughts on positive marital burnout is significant. To examine the indirect impact of irritability on marital burnout through negative repetitive thoughts as a mediator, the Sobel test was employed.
Additionally, the Variance Accounted for (VAF) statistic was utilized to determine the magnitude of the indirect effect through a mediator. The results of these analyses are presented in Table 5.
Based on the data presented in Table 5, the indirect t-statistic (T-Sobel) between the mentioned variables falls outside the range of (1.96 & -1.96), indicating that the hypothesis regarding the indirect effect of the irritability variable on marital burnout is accepted. Thus, in addition to its direct impact, irritability variables also indirectly affect marital burnout through repetitive negative thoughts.
Furthermore, the VAF statistics reveal that 35.9% of the impact of irritability on marital burnout can be attributed to its influence on repetitive negative thoughts.

Discussion

This study aimed to design and test a causal model of marital burnout through irritability: the mediating role of repetitive negative thoughts in infertile women.

The findings indicate that there is a positive and significant effect of irritability on marital burnout in infertile women. The obtained results were in line with the findings of Mikaeli et al. (2023) (11); Hammett et al. (2021) (12); Namdarpour and Balghan-Abadi (2019) (14); Sandberg et al. (2018) (13). According to a study conducted by Sandberg et al. (13), it was found that perceived relationship aggression leads to lower sexual satisfaction for both partners. Based on social exchanges and behavioral theories, the relative dominance of positive to negative behaviors in dysfunctional marriages can be used to distinguish functional marriages from non-functional marriages. In dysfunctional marriages, couples tend to experience more negative behaviours than positive ones, which ultimately leads to lower levels of satisfaction (12). Spouse aggression towards each other is one of these negative behaviors that may be the underlying cause of dysfunctional marriages; in

fact, relationship partners who exhibit higher levels of aggression are less likely to compromise in their relationship (24). Another possible explanation for the cross-sectional relationship between aggression and satisfaction is that dissatisfaction in the relationship may predict partner aggression. This perspective suggests that relationship distress itself can be a unique risk factor for spousal aggression (25). Therefore, the connection between aggression and satisfaction might not be as longitudinally strong as previously thought, or it may not show consistent patterns longitudinally. The relationship between aggression and satisfaction may also be reciprocal, with aggression causing relationship distress and, at the same time, relationship distress causing aggression (12). In simpler terms, infertile women might engage in provocative behaviors such as violence and aggression as a result of the unpleasant feelings they experience, which can contribute to marital issues such as marital burnout.

The results showed that repetitive negative thoughts directly and significantly affect marital burnout in infertile women. These results were in line with the results of Falahati and Mohammadi (2020) (5) and Gumus and Kislak (2011) (17). Automatic negative thoughts are accompanied by feelings of helplessness. Ellis believes that dysfunctional negative mental representations occur when a negative event begins, and negatively dysfunctional designs are exploited for the wrong reasons. According to Beck, dysfunctional thinking is not only based on the criteria of perfectionism used by individuals to judge themselves and others, but also because they are inflexible, extreme, and resistant to change  (26). In women who have been suffering from infertility for a long time, spontaneous negative thoughts have caused a gap in emotional relationships and isolation from the husband, followed by marital burnout.

The results also pinpointed a significant indirect effect of irritability on marital burnout of infertile women through repetitive negative thoughts. This indicates that repetitive negative thoughts act as a mediator between irritability and marital burnout in infertile women, explaining approximately 35% of the impact of irritability on marital burnout in infertile women. No research was found that directly correlated with these results. Based on the above, it can be hypothesized that when infertile women experience anger over their problem due to the negative excitement they experience and are not understood by their husbands, this emotional emotion is reflected in the form of negative thoughts repetitive in mind and considers every event in its negative aspect, which leads to more externalization and aggression towards the spouse, and after repeating it, marital relations are damaged, which will lead to marital burnout. In fact, the mediating role of repetitive negative thoughts in the relationship between irritability and marital burnout of infertile women showed that by providing training based on reducing repetitive negative thoughts, the effect of irritability on marital burnout can be controlled to some extent.

The findings of this research showed that irritability is an important and influential variable that can challenge the ability of infertile women to adapt, because irritability is more common in women, paying attention to this finding can reduce the psychological problems of these women. This study did not explore certain spouse characteristics, such as occupation, education level, and the man's marital satisfaction that can cause mental disorders in infertile women, warranting further investigation in future research. Additionally, it is essential to interpret the results of this study while acknowledging its limitations. One such limitation is the reliance on self-report scales to assess research variables. It is recommended to conduct further research focusing on additional factors such as personality traits or external stressors, as they may provide a better understanding of the relationship between burnout and irritability over time. Knowing the orientation of the irritability-burnout relationship is also crucial for prevention and intervention programs for couples in anxious marriages and for irritability treatment programs.

Conclusion

Overall, the findings of this study revealed that, in addition to its direct impact on marital burnout, irritability can also exert an indirect influence through mediation of repetitive negative thoughts. Considering the indirect effect of irritability on marital burnout via repetitive negative thoughts, controlling irritability in infertile women may result in is reduction of repetitive negative thoughts, consequently lowering their level of marital burnout.

Acknowledgements

The authors would like to express their gratitude to the women who participated in this study.
Conflicts of interest

Authors declared no conflicts of interest.