Ha. "All cool with everyone involved". Great in theory. They might tell you it's all cool, they might get along on the surface, but if you're casually dating multiple women who know each other, it can be the best or worst thing ever. I was dating 2 sisters once who were "cool" with it but that didn't stop the abrupt "JANICE ISN'T PICKING UP HER PHONE ARE YOU WITH HER? I HEAR HER VOICE! I'M COMING OVER" phone calls which would be followed by a calm "Oh I just wanted to hang out with you guys too, I don't care what you do with her" conversation. Uh huh. They both did the same thing, even left dates with other guys a few times to swoop in for the Charlie Bravo. Women. It's always a trap.