Aim: The present study was conducted with the aim of investigating the effectiveness of cognitive behavioral couple therapy on improving marital conflicts and the quality of relationships of betrayed women. Method: The method of this research was a semi-experimental type of pre-test-post-test and follow-up with a control group. Using the targeted sampling method, 30 women who had been betrayed in one district of Tehran were selected, and they were randomly assigned to two experimental and control groups. Marital conflict and relationship quality questionnaires were used to collect data. Then, the experimental group received 8 sessions of 120 minutes of group training of cognitive behavioral couple therapy, but the control group did not receive any intervention. For the follow-up phase, the questionnaires were implemented again two months after the post-test. Findings: The results showed that there is a significant difference between the marital conflicts and the quality of women's relationships in the pre-test, post-test and follow-up stages. Conclusion: Cognitive behavioral couple therapy can effectively increase the quality of relationships of betrayed women and reduce their conflicts and improve the problems related to intimacy, lack of agreement, interest, affection and commitment and personality compatibility of couples.