In recent decades the family in Iran, under the influence of internal and external factors has changed. One of these changes is the increase of conflict in the family and the consequent collapse of the couple's relationship, which has become one of the main challenges of the contemporary family. The aim of the present study was to compare the causes of marital conflicts in the last three decades (1991-2020) with a comparative method. by Convenience Sampling were selected 225 conflicting couples (450 people) married in three decades (1991-2020) were selected from couples referring to a counseling and psychology center in Tehran in 2019-2020 and 19-factor checklist of marital conflict It was given to them to complete The results of analysis of variance showed into marital conflicts trajectory of those married during the three decades (1990s-2000s-2010s) indicated that there are significant differences in factors of frustration, the absence of care and support, economic and occupational problems، power structure, unattractiveness, sexual dissatisfaction, past romantic relationships problems, personality and behavioral problems and religion issues. that some factors related to marital conflicts depends on time conditions. as a result, for every decade, the identification and then determination of the roles of these factors in marital conflicts is suggested.