Should I just remain oblivious?

I want to give a bit of background here without being too long winded, as I'm sure my story is not a very unique one. Also I'm not sure if it's okay to ask these kind of questions here but I didn't see anything agaisnt it in the FAQs.I'm not sure how releveant this is, but my adult relationships and sexual relationships have all been with women. My first sexual experience period was with another guy my age when we were both 12-13, and it happened on an almost daily basis for a whole summer. I think that partially changed my sexuality but I still feel straight for the most part.Anyway, I'm 28, I'm in a relationship with a girl that I'm pretty happy with. In her mind I am a completely straight dude (maybe I really am, I don't know) but I have always had certain unfulfilled desires, or at least what I perceive to be unfulfilled desires. The question comes in when I start to think about if I should act on them or not so I will know once and for all. I know I would be happy going the rest of my life and never going there, but part of me in the back of my mind feels like if I don't at least try something with another guy I will never know, and that maybe it would be kinda sad in a way to not fully explore myself. Should I just keep it as a happy unknown fantasy to think about in my own mind occasionally, or is it worth risking my relationship and possibly having to deal with new realizations about my sexuality to give it a shot?