Confused and Maybe Bi, and I have a girlfriend?

So I, a male, just finished my freshman year of college. I have been in a serious relationship with my girlfriend for a year and a half, its occasionally rocky but definitely going good. Ok heres the kicker, ever since I was 12 I've been extremely curious about guys. I'm not attracted to my straight friends at all, but I am attracted to guys I'm not close friends with, especially if I can tell they are gay. I am more attracted to women, but the curiousity kills me. Idk if I would actually keep the lifestyle if I tried it, but I feel the want to try, but I can't lose my girlfriend-she might be the one, I just wish I met her after I got to try things out. Any advice for this confused kid? PS My girlfriend would not be understanding if I told her