I can tell you about my weird experience. I don't think that I could have handled it when I was younger but I am fine with it now as I'm a bit older and don't care about this kind of stuff as much.

My current partner, Amanda who I've been with for 13 years briefly dated my roommate at the time before we got together. It's kind of a funny story actually. She was friends with him to start with, but she actually really liked me.

I was too stupid to notice that she liked me, so my roommate started to put the moves on her pretty heavily. He didn't want me to figure it out before he could get with her. hahaha.

So after we got together it was weird with my friend to be sure. It took me a little while to get over it, but now we've been together for so many years that it seems silly that I ever cared.