The failure of couples in resolving marital problems could be expressed in various forms so that each of them can be a threat to the health of marital relationship. One of the causes of marital disputes is disaffection which is common in many couples and is influenced by many factors including differentiation, neuroticism, forgiveness and martial conflict. The purpose of this study was to examine the causal relationship between differentiation, neuroticism and forgiveness and marital disaffection by mediation of marital conflict. For this purpose, a sample of 300 married male teachers in elementary, middle and high schools of Estahban participated in this study. Participants were asked to respond to the Marital Disaffection Scale (MDS), the Revised Differentiation of Self Questionnaire (DSI-R), the Neuroticism of NEO Five-Factor Personality Inventory (NEO-FFI), the Forgiveness Scale (FS) and Sanai’s Revised Marital Conflicts Questionnaire (MCQ-R). The results showed that all coefficients of the path between variants were statistically significant. Moreover, the direct paths of differentiation, neuroticism, forgiveness and marital conflict to marital disaffection were statistically significant. The direct paths of differentiation, neuroticism and forgiveness to marital conflict were significant as well. Also, the results of this study revealed that the indirect relationship between differentiation, neuroticism and forgiveness and marital disaffection was also significant through marital conflict. It seems that marital disaffection is a complex phenomenon which is influenced by various factors such as differentiation, neuroticism, forgiveness and martial conflict.