Introduction: Infidelity, as a main cause for marital maladaptiveness and divorce, has important effectson victim’ s family and mental health. This study aimed to identify and explain the cognitive reactions andexperiences of women victims of infidelity. Method: The present study employed a qualitative approach along with the interpretative phenomenologymethod. The study population consisted of women victims of infidelity in Tehran (Shemiranat), Iran, inyear 2016. To do so, 18 women who were victims of infidelity were selected through purposive sampling, and investigated by a semi-structured interview. The data elicited from the interviews were analyzed usingthematic analysis method. Results: The data analysis resulted in two main themes, 11 subthemes, and 61 initial concepts. As the firsttheme, “ maladaptive cognitive reactions” consisted “ porous religious beliefs” , “ suspicion” , “ obsession” , “ damage in the meaning of life” , “ maladaptive decision-making” , “ thinking to punish the guilty” , “ negative self-evaluating, and “ thought disorders” as subthemes. The second main theme was “ adaptivecognitive reactions” consisting “ positive defensive thoughts” , “ appeal to religious beliefs” , and “ peaceseekingthoughts for the decision-making” as subthemes. Conclusion: From cognitive aspect, the infidelity is not experienced homogeneously by all womenvictims, and the effects of infidelity can be either maladaptive or adaptive. Personality, religious beliefs, having children, and spousal relationship quality contributed to the women victims’ reactions. Given thefact that the findings have been elicited out of a native study, they may play a vital role in developing theintervention packages.