"I think it has to do with our cultural notions of what it means to be a man and what ... the social expectations are for masculinity," the study author, Christin Munsch, an assistant professor of sociology at the University of Connecticut, told CNN.
Being economically dependent on their wives may threaten their manhood, Munsch said, and having an affair is a way to re-establish their masculinity, even if it's all done subconsciously.
"There's plenty of great literature showing how when men in particular undergo gender identity threats, they engage in hypermasculine behaviors," she said.