Game theory and playing around
Game theory can tell us something about how and why gay guys tend to hook up.
In the straight world, everyone's familiar with the dynamic. All over the nature channels, females bear the brunt of child-rearing by being pregnant, and produce fewer eggs than males do sperm, so it pays for women to be choosy about mates who can provide for many offspring. Men tend to want as many partners as possible, because that's what's going to get them the most offspring.
These aren't conscious choices. They're tendencies in our psyche that, over the long course of evolution, got the most genes into the next round. So they win.
In homo couples, though, the gender tendencies remain the same. I've noticed a curious dynamic among single guys, monogamous couples, and open relationships.
I've found that many single guys think open relationships aren't tenable. What's more, when they feel this way it's often vehemently against non-monogamy. You'll hear from single guys that open couples aren't as real as monogamous ones, that non-monogamous guys are cheating on each other all the time, that they're destined to fail.
I don't agree or disagree. I'm single and I'd like a partner eventually, so from my perspective it just doesn't make sense to sleep with part of a partnered couple, because there's no chance of it turning into what I'm really looking for. Even if the sex is great, there's little chance of me getting it all the time, because I'm essentially on the outside. And if I fall for the guy, I'm screwed.
So for a single guy, it's advantageous for more guys to be monogamous, because then other potential partners aren't distracted and taking up valuable time with partnered guys when they could be dating me.
But someday I might be partnered. What happens then?
Humans tend to mate for life, but in the situation where we evolved, a lifetime wasn't that long. What are people supposed to do now that relationships last decades past what we're designed to expect? For gay men, it's natural to expect that the eyes of one or both might wander. Why not save the marriage by laying out some ground rules?
So for partnered guys, the optimal solution is to have everyone on the playing field be either single or non-monogamous, too.
One group "wins" when everyone keeps with tradition. The other group, which started out keeping tradition by marrying off, eventually "wins" when everyone breaks tradition.
There's no solution to this one. You just have to hate the game.