Back in the day there was the code: Bros before hoes. Come to think of it, there were just two instances where this could have happened but I wouldn’t do it. I have never been in one of those weird relationships where a friend asked me to have sex with his partner or gave me the green light to sleep with one of his partners. When I was young I was too principled to do either. This is one of the reasons why I see escorts instead. It’s a lot less complicated. There is much less potential for collateral damage and weirdness. I’m not saying I was right but if you can spend 200-250$ and save a relationship than why not?
There was a situation when I was seduced by my SO’s ex-best friend. We were never caught but my SO suspected something. It destroyed their friendship and before it did the other woman used it almost to blackmail me. And believe me, I could have done a lot better with HPL or Mirage without all the fallout.