I'm happily single and I have a buddy who is in a committed relationship. Occasionally the topic of cheating comes up when we talk about past experiences we've had. When I told him that I would not be opposed to hooking up with a hypothetical girl who's taken, he said something to the effect of "don't be a dick."

Back when I was still in an LTR, I probably would've reacted the same way. And for a time, after discovering I had been the "victim" of cheating, I would've reacted especially aggressively. But besides the very possible risk of provoking a girl's territorial and insecure partner, I don't see a real ethical problem with hooking up with a taken woman.

Now I can see 2 possible ethical objections to it. First is idea that monogamy only works on a societal scale when everyone pressures everyone else (especially women) to honor their commitments, and so you'd be undermining the very fabric of society by participating in an affair.

To which I'd say; sounds good. I'm not really interested in monogamy anyway, and it's probably unnatural to begin with, hence the fragile social norms necessary for its maintainence.

For all the complaining I see about how slutty girls are these days, I can't imagine that men would really want to live in a world without sluts and the possibility of noncommittal sex. How many guys here really want to have sex with 1 woman for the rest of their lives anyway?

The 2nd possible objection to home-wrecking is I think what most of us intuit by default without ever articulating it: Since a guy and a girl have made a committment to eachother, explicit or otherwise, to remain sexually exclusive, third parties ought to also honor that committment.

When you spell it out like that, it becomes pretty clearly untenable. In what other situation is a person morally obligated to honor someone else's word? Before you buy a car, would you ask the seller if he or she had previously promised to sell the car to someone else? Of course not. Those agreements aren't just not your problem, they're not not even any of your business. Expecting anyone to honor or value commitments that they didn't make and had nothing to do with is crazy. (And at least a car is a tangible, finite resource. There's a virtually unlimited amount of sex to go around.)

Besides that, the dating game nowadays involves notoriously "complicated" and ambiguous levels of committment. Even within marriage there is a spectrum depending on cultural traditions and whether a couple is separated or not.

With all these shades of grey (no pun intended), it would be difficult to assess the terms of any union from outside the relationship, and to do so without overstepping boundaries with regards to privacy would be impossible.

Are there any other ethical problems I'm missing?