What to do

So I am a man in my late 20's who identifies as straight. I have always fantasized about being fucked by a guy. I have gone out and had sex with guys a few times and generally enjoyed it. I continue to fantasize about kinky sex with men. I however have never felt any desire to have a relationship with another guy and don't find men attractive generally. I just like the sex.I currently have a girlfriend who is amazing and likely my future wife. How do I deal with these urges while being in a committed relationship? We have a lot of great sex but at times I can't stop fantasizing about gay sex. Anyone else have this issue?