We recently learned women are now scoring higher than men on IQ tests, and that ladies currently make up the majority of primary breadwinners.

But new research shows that if there’s one group that isn’t pleased about all that, it’s macho guys.

The study, which focused on the way gender roles have changed over the last 40 years, found that when macho guys are with women who earn more than they do, it puts a real strain on the relationship.

So what constitutes “macho”? The need for a man to control his emotions and to reject femininity — and the more the guys in the study identified themselves that way, the more the income gap bothered him and the more likely they were to say they had problems in their relationships.

Men who are less traditionally masculine, on the other hand, didn’t seem to care as much if their partners out-earned them, and typically reported having a good relationship with their wives or girlfriends.

In other words: guys, choose your battles carefully. If you embrace those macho stereotypes too much, you could find yourself single with a quickness.

[LiveScience]