When I was in college, I once dumped this girl for her much hotter roommate. But that didn’t stop me from sleeping with her constantly.
The first wasn’t fond of the second when I switched from the one to the other, so they never talked. Somehow I got away with screwing both girls in this house for a whole year.
After that year, the hotter one graduated, so while I was still “officially” with her, it was much easier to sleep with the first girl who was still around. Then I graduated and left, and was still with the hotter one.
I eventually grew up, and never wanted to cheat on her again. After another two years, I honestly thought she and I would get married. Then she left me for some other schmuck. I totally deserved it, but I cannot tell her that.