The saying is "BIRDS OF A FEATHER FLOCK TOGETHER" 

I've witnessed lots of people (MEN & WOMEN) who aren't comfortable with there significant other hanging out with anyone other than people of the same status!!! Meaning... Married people want their spouse to hang with other "Married" men or women... Single women only want to hang out with other "Single" women... or vice versa....

I FEEL THAT WE ALL SHOULD BE ABLE TO MINGLE AMONGST WHATEVER RELATIONSHIP STATUS... HOW WOULD YOU FEEL ABOUT YOUR SIGNIFICANT OTHER HANGING OUT WITH SINGLES???? AND WHY????