Since this thread is hypothetical, and since it's an interesting question, I'd like to play devil's advocate and put forward the idea that perhaps we, as women, put too much emphasis on the physical act?
Full disclosure: My former marriage had a million terrible problems, but as for as I know, there was no cheating. If a man I loved cheated on me, I'm sure it would completely break my heart, and it might well burst the bubble sufficiently that my feelings could never recover. In what I'm about to say, I'm only speaking hypothetically.
But. Men see non-committed sex as much more of a separate thing, perhaps much like getting a massage, as far as I can gather. If he didn't love the woman, maybe it's not worth throwing away a whole life together over a bit of the old in and out? It means nothing to the man, so perhaps it shouldn't mean so much to us, either?
What do you think?
My head says that it's crazy to throw everything away because he had a few minutes of pleasure, but my heart says it would be shattered.
Personally, I think it's mad that we build our entire lives on something as ephemeral as sexual attraction, seems like an obvious recipe for disaster, but I'm not sure what the alternative is.
Maybe people should marry partners who are really similar to them, with whom they have everything in common, and with whom you have a great friendship, and then both just date and have flings and stuff with people you would never marry, like you did when you were young and free.