Introduction: Infidelity seems an individual phenomenon at first glance, but considering the consequences and disadvantages on the family, raising children and also health and safety of the community, it is considered a hidden and serious social pathology. The present study was designed to determine the relationship between personality traits, early maladaptive patterns, optimism and pessimism with justification of infidelity in married couples.

Methods: In this descriptive-analytical study, the research community was all married couples referred to counseling centers in Golestan Province in 2015 with a history of marital infidelity among which, 100 samples (50 males, and 50 females) were selected by the simple random sampling method. The research instruments were questionnaires of the personality traits of NEO, the early maladaptive patterns, the optimism and pessimism and infidelity justification. The collected data were analyzed using descriptive and inferential statistics with the Smart PLS 2 software and the partial least squares method.

Results: Results of the study showed a significant inverse relationship between early maladaptive patterns (β = -0.612 & T = 5.344) and optimism and pessimism (β = -0.195 & T = 2.273) with justification of marital infidelity. There was no significant relationship between personality characteristics and justification of marital infidelity (β = -0.21 & T = 1.781).

Conclusions: In this study, most of the correlations were between early maladaptive patterns and justification of infidelity; therefore, it can be used to identify people at risk.