Purpose: In a general and comprehensive definition, infidelity 
or extramarital relationship is the violation of the assumed or 
determined agreement of the couple regarding emotional or 
sexual exclusivity.
Materials and Methods: The aim of the present study is to 
quantitatively combine the results of these studies using the 
meta-analysis technique. In this meta-analysis, ten eligible 
studies that were conducted between 2012 and 2021 were 
analyzed with CMA2 software. The selected researches have 
been carried out by means of a survey method and by using 
the standard questionnaire tool of attitude towards marital 
infidelity (Whatley) and attachment styles (Hazen and Shaver) 
in different statistical societies.
Findings: Various researches have been conducted on why 
and how people get involved in extramarital relationships, and 
the impact of psychological factors such as attachment styles, 
personality traits, and primary incompatible schemas have 
been investigated, but the results of researches on the intensity 
of the impact of these psychological factors are different.
Conclusion: The results of the statistical evaluation show the 
heterogeneity of the effect size and the lack of publication bias 
of the studied studies.