What can possibly be the cause of such a pattern in the society you posit? It's much more likely that such a gendered behavior will disappear; the causes of the existing pattern are sexism + income & wealth inequality between men and women, so in a society where neither exists, there is no material condition that supports such a pattern. Further, there won't be any matterial support for the predominance of heterosexuality either. I guess when it comes to gender, many men avoid inconvenient materialist explanations.
Yoshie