Only speaking for myself here:
I believe souls are genderless, and that people fall in love with souls, not bodies; so if I love someone who happens to be male bodied then that's okay.
I used to think I was a lesbian, then I met this guy who I had an instant connection with, almost like we met before; then I started changing my mind. I later got married to a different guy, but that was disastrous....
While I can love someone in a male's body, I now realize that I am in no way physically attracted to their bodies. I don't like the way they taste, smell, or feel. I've always enjoyed the taste, smell, and feelings of women, so that's where, at least on a physical scale, I am planning on staying for now on.
I am not talking for the other guys on here; but I know for myself (and also some lesbians who I know) that sometimes you start dating men because that's either what's expected or that's what you think you want, like, you're trying to be normal. I also realize now that at the time when I thought I was physically attracted to men, I was getting confused between what I thought was attractive and what I wanted to look like; I also spent a bit of time dressing like the women who I thought were hot. Yeah... it was a bit of a confusing time, but now I know I am trans and that male bodies just don't do it for me.