Anecdotally, I had five woman in my CS program out of 100 students (I know, pathetic)... but all five of them graduated. Can't say the same for the men.

My wife was an Electromechanical engineer, in her program they had the same number of woman but a higher percentage because there were fewer students in the major in general. I think they all graduated although a couple of them had to retake some courses so they didn't finish on time.

But my guess is it is a cultural thing not an aptitude thing. Woman have certain standards they need to live up to that aren't necessarily expected of men. Especially in male dominated majors where I have definitely observed the attitude where woman need work harder to prove they deserve to be there than men.

Edit: summary: my hypothesis is men fail out due to apathy since they are told from birth that college is their right and expectation whereas woman have something to prove. As that changes I expect either the woman will become apathetic too or the men will step up their game. Either way, a system out of equilibrium seeks balance.