The aim of this study was to investigate the mediating role of differentiation in the relationship between meaning of life and attachment style with love in couples in Tehran. Participants in the present study were 238 couples in Tehran who were selected by available sampling. The love questionnaire of Iranian-Islamic scientists (1399) was used to measure love; Scorne self-differentiation questionnaire (DSI-R) was used to assess differentiation; The Life Value Questionnaire (LRI) was used to assess the meaning of life and the Attachment Style Questionnaire Hazan & Shaver (1978) was used to assess attachment. The collected data were analyzed using Spss and AMOS software to test the significance of Pearson correlation coefficient and statistical model test on couples in Tehran. After analyzing the data, the results showed that there was a significant relationship between the meaning of life and attachment style, attachment and love style, differentiation and love, differentiation and love, and differentiation played a mediating role in the relationship between meaning of life and Attachment style with love is significant and its statistical model has a good fit.