GQjockIt kind of ruins what you're trying to strive for in a relationship to begin with
to have one guy who's completely committed to you and the other way 'round
I've never understood why a wholehearted commitment to someone "naturally" means "forsaking all others," or why the goal of a relationship should always obviously be one
guy. The moment you make a claim to never, ever being able to love another person, you set yourself up for a high likelihood of failure and create a breeding ground for jealousy.
Our hearts are large enough. And loving more doesn't cheapen the love we already have.
I had a triad relationship throughout grad school (with another man and a woman, and if you don't think that
took some adjustment...) The turning point for me came with realizing (a) I am not absolutely everything my partner requires or wants out of life, (b) he isn't that for me, either, and (c) we both love the person who has become our best friend because of points (a) and (b). We'd had an open relationship before that (he was bi), which made the transition a bit easier, but we closed the relationship after Liz joined. All around, it had about the same amount of crap and candy as any relationship. Just different kinds.
Some references, with varying degrees of helpfulness:Redefining our Relationships: Guidelines for Responsible Open RelationshipsPolyamory: Roadmaps for the Clueless and HopefulThe Threesome HandbookFuck You-Aloha-I Love YouWorld Polyamory Association
Most of them aren't strictly gay, but really - it's tough to have a triad relationship that isn't
queer. And, sad to say, there's a relative shortage of intelligent gay literature. If you're a theory nerd, check out anything by Michael Warner, who is the Eddie Izzard of queer studies.
Best of luck! And whatever you decide, I'm glad you're open-minded enough that the very thought of a different valid relationship doesn't make your anus clench in fear. ;-p