Introduction: Marital infidelity is an issue many couples’,therapists face and is one of the most important reasons for getting divorced. The factors related to infidelity can be included in three domains: individual differences, the nature of the relationship, and environmental conditions. This study investigated the role of emotional schemas and personality traits (as individual differences) in infidelity. Materials and Methods: In the present study conducted in Mashhad, Iran, 320 individuals were selected by the convenience sampling method (including 160 individuals with infidelity experience and 160 individuals without experience of infidelity as controls). They fulfilled the Leahy Emotional Schema Scale and Personality Inventory for DSM-5. The data were analyzed by Multivariable Analyze of Variance and SPSS-26 software. Results: The results showed that the lack of inhibition personality traits in individuals with the experience of infidelity were higher than in the control group. The “, guilt and blame”,emotional schemas were higher in group with infidelity experience than in the controls (P= 0. 012, P= 0. 025). The “, validating”,emotional schema in individuals with infidelity was lower than in the control group (P= 0. 011). No significant differences were found between the other emotional schemas. Conclusion: According to the results, infidelity prevention can be done by modifying personality traits and emotional schemas through schema therapy and emotional schema therapy.