I dont want to pick sides?

so when it comes to friends i am there but this one i need advice. so one of my friends asked this kid if he would go to semi and he said no. she asked again but he still said no. so the girl starts to cry but she needs to get over him, plus i told her he has a gf. then this other girl tries to make my friend feel better by yelling at the guy at lunch saying **** you. which was unnecessary i think. after when were leaving lunch there saying that the guy called the girl names but he didn't. so now she is going to make a fight for no reason and she practically started the whole thing. so i want to tell her to cut the crap and leave the poor kid alone. he said no and he wasn't mean about it. so what do i do? and how? without starting a war.