The Excitement and Fear of a Man

The biggest excitement and at the same time the biggest fear for me is to be with a man in my own age of 22. I would love to try sex with a man as my only experience of sex is with a woman. In my head I picture myself sucking another man's cock and him sucking mine. But what if I enjoy that more than the sex I have with my girlfriend? Would I have to break up with her and miss her forever? I fantasize about this at work, in the shower and even in bed with my beautiful girlfriend next to me. Maybe a secret male lover is what I am searching for.