The younger the guy, the more he will play the field. The older the guy, the more he will settle down in a monogamous relationship. This is a matter of our male hormones, and simple maturity, regardless of our sexual orientation. Most men are remarkably alike, regardless of whether we're straight or gay.
And likewise, men of all types can suffer from a mid-life crisis, and will jump the tracks as they begin to enter middle age. Again, men are men.
So to answer your question -- yes, we guys can be in a committed relationship. I've seen it begin right out out high school, and last until their deaths. And that's partnered with both women and with men, as orientation dictates.
And don't overrate the fidelity of females. Some studies have shown a lot of straying on the distaff side, too, though it often doesn't get a lot of notice.
I think the constant is that when you're with someone you truly love, a man or woman, who meets all your emotional needs, you simply have no interest in looking elsewhere. I know countless gay relationships that "work" and I like to think that I'm in one myself. I hope you find one, too, if that's what you want.