Just speaking from my own experience here. I dont believe in platonic relationships. Unless the guy is gay or impotent. No just impotent, because gay guys would still do it. LOL..

My ex had a lot more guy friends than girl friends. Also her "best friend" was a guy, she told me this in the beginning. I trusted her but in the back of my mind was still a bit leery.

For good reason. She slept with her best friend and another friend. Who knows how long they have been sleeping together, but I was not there to find out. I was gone real fast.

Bottom line a guy will always want to fuck his girl friends, he's hoping to be that shoulder to lean on. Or just hang out get drunk and have casual sex as if its nothing.