problem with the GF? maybe

ok so maybe it's timing or my fault or some other BS reason
but it seems that whenever me and my girl are together and hanging around her friends,
she's not only distant and cold, she's mean. she totally treats me like crap. and i'm supposed to be ok about it once we talk/argue and she apologizes. EVERY TIME.
like it's becoming difficult to draw the line. she doesn't usually act like that in private, and i don't wanna be the dude who straight up calls her out and sets the record straight in public in front of her friends... cuz that'd be dick.
right?
idk.
it's just really bugging me to the point to where i actually have to write something like this. to where i actually have to tell people, "hey. i have a problem with crystal." and it didn't used to be like that, but lately i just feel unimportant and unappreciated when it comes to her.
so what do i do?
i'm usually the one answering questions like this, but i guess i'm asking this time.
help ya boy out!