Bust up

Someone you have sex with on a consistent basis but would never be in a serious relationship with due to them missing key attributes of a significant other. Not to be confused with a bust down. Bust downs are solely for sex while “bust ups” have potential to be more if they corrected certain things.

Friend: “Are you bringing Brittany home for the holidays?”
Me: “Nah, she’s not quite on that level. She’s just a “bust up”.