For years I've thought I was bi. But recently I've been feeling less and less attracted to women. Sex with a woman doesn't interest me unless it's with a trans woman or pegging. I find women attractive but my experiences with women have ruined dating women for me. I've never been into penetrating a woman either. I'm starting to think my bisexuality was a coping mechanism because I come from a Christian family. Could I just be realizing that I'm gay now and that my bisexuality was a phase? (I have no problem being gay by the way)
Bisexuality usually isn't a "phase" - it can be, everyone is different - but for a lot of gay men, it's a coping mechanism as part of the bargaining process. I went through this myself about 5 years ago when I was struggling to accept I was gay. I had several girlfriends, although I wasn't really into sex much. I had(have) a high sex drive, but just wasn't interested. I thought I was missing something. When men started to enter the picture, it started to become clear that I am waaaay more into dudes. Saying you're bi is a way to skirt the issue of you sexuality, usually because of cultural norms and attitudes from those around you. In a sense, you're going through a loss: the loss of your straight identity. When you're gay, people can and do treat you differently. Sometimes in a different better way, sometimes not. But saying you're bi is a way for some keep a sort of "half-identity" and not give up their straight identity completely. "See mom, I like boys too, but I still won't disappoint you, I can always marry a woman, have kids and be happy." This is not to say there aren't legitimately bisexual males, there absolutely are. I'm talking about gay males who go through this particularly process, as I did, and I have several close gay friends who did as well.
Is it important? I know how important labels can seem, but at the end of the day they are just convenient shorthands for far more complicated truths. If you do not feel the need to date women anymore (or never really have) enjoy your gay life. If your attraction to women starts again some later day, feel free to date them again. There is really no need to decide now what you will do for the rest of your life.