Camilla an ex member of fifth harmony attended the grammys with her boyfriend Shawn Mendes.
Apparently according to some people this "perfect " couple is rude towards their fans for asking for pictures and autographs.
Ariana has never been much of a fan of their relationship. She found odd how they broke up and got together and that they got together 1 month after Cabello's breakup with her ex.
This may make them angered and want to hurt Grande and tonight was the perfect opportunity for them to do so.
Unfortunately if they have done this they have caused so much drama and trouble.