Her ex-boyfriend had multiple personality disorder.

I had a boyfriend with Dissociative Identity Disorder (formerly known as multiple personality disorder, or split personalities). On numerous occasions, I watched him switch identities right in front of me. He only knew of three identities, but I counted at least four. At one point, he switched WHILE we were having sex to his most insane identity — I was on top and looked down at him, and he had this creepy smile and I just knew. Fucking terrifying. Anyway, one of his personalities was female, and after a time of identifying as various stages of bi/gay, he finally decided/realized that he truly felt like a woman, and has been undergoing sexual reassignment therapy for the last few years.