I'm sure someone can write a decent romcom from this.
when she tells the story it is much funnier, and sweeter.
the problem is the set up is important.
I was a womanising serial cheater, yet I never cheated on the ex GF wiht the current wife. we were broken up when we hooked up, sure we had sex the day before I hooked up wiht the current wife, but that was a FWB arrangement. she grew feelings and came knocking on my door the night I hooked up wiht the wife for the first time (seriously bad timing) to try and mend the relationship. when she saw the current wife in my bed, she sugjested a threesome. I turned her down, did not think the SO would be game.
really glad I did that. it would have turned the hook up into just that, a hook up wiht no meaning, what happened instead is I found the women of my dreams.

