I think it's because they rely on women for affirmation. I knew a guy in highschool, he had friends, but they were that "punk" crowd. Fast forward about 6 years after highschool and he ends up dating my gf's cousin. They break up after awhile. He seemed like a decent guy, and he didn't act feminine at all, but then a few more years later he's now a she. I think he had an abusive step-dad and a mother who didn't give a shit.