Maybe it's just the community of gay men that I hang around with, but it's seemed to me that poly and/or some form of open relationship is rampant... It almost seems weird to me to hear that a gay man is monogamous based on the behavior and philosophy of most of the gay men I know.
I've never selected friends or social environments based at all on sexual orientation (though lately I'm actively seeking to make more gay and bi male friends). I mention this only because it helps you to see where I am coming from; I'm not, and never have been, part of a gay or queer subculture. This fact means I haven't got a particularly strong sense of what's going on "out there" in the big, bad gay/queer world.
I have known a fair number of bi-, gay, queer men. And for a while I was hanging out with some Radical Faeries at one of their "sanctuaries". The faeries I knew generally inverted the mainstream culture's monogamism, meaning that they looked upon monogamy with a bit of snooty superiority and contempt. Some of these were polyamorous--but few. (This was a long time ago.) One of them even asked me to be one of his lovers!--which weirded me out, since I hadn't yet come to understand and embrace polyamory. Love, to me, still meant monogamy.
Getting to the point.... My overall experience is that, yes, many, many gay/bi/queer men have open relationships of some sort or another, but few are actually polyamorous. Sexual non-exclusivity is one thing and polyamory is quite another -- because poly is
primarily about creating
loving relationships, usually passionate loving relationships, and it looks very much to me that most gay men with lovers are as possessive and fearful of loss as most straight folk are.
Often, gay male lovers will work out an agreement to the effect that each agrees that the other can have "sexual freedom" --, but have a verbal contract to the effect that "sex is just sex" and "it isn't okay to fall in love" with an outside person (sometimes called "trick").
Gay men often seem to have their erogenous zones split off from their hearts, and this sort of thing seems to be a symptom of that. If one hasn't had that split happen to them, or is deliberately healing that split (however partial it may be -- and I'm one of these, with a very mild case), having "just sex" --without emotions in the love-spectrum-- is a concept akin to "North of the North pole". Yes, the body can experience intense pleasure by rubbing body parts with another body -- but why bother when what we really want is to love and be loved in this way? And isn't there something rather deceptive and crude about using another person as an inflatable doll in a masturbation fantasy?
Of course, not all loving relationships will be alike, or will be long enduring as such, but I'm not at all interested in loveless sex. It stands in the way of where I'm travelling to.
Pardon me the labyrinthian nature of this wandering post. I must leave it rough, for that's what wants to be said, and I'm still learning what I have to say anyhow.