>>87801098IIRC, she accidentally outs Peter to a villain and, to throw suspicion off of him, decides to steal Pete's webshooters, gives them to Flash Thompson, and spends all day flirting with him and hanging out around town with him so that the villain will try to kill him instead of Peter.
I don't quite recall, but I think MJ gets killed in the ensuing crossfire and Pete basically severs ties with Felicia.