That felt savage. "You can go ahead and forget the little mistake that you like me cause I'm going out with someone else okay? I just want you to be happy!" Like, wow. Ouch. Even Saku points out how odd it was that she said that and not him in an effort to make things less awkward. Literally nothing he said acknowledged accepting making a mistake regarding his feelings, yet she feels the need to parrot that "SaKu TOtAlLY REaLIzEs hE WaS WrOnG anD wiLL BE LoOKiNg ElSewHeRe NoW" to literally every person on the planet as if she's trying to convince herself. He literally just said "I get it, I'm happy for you" and pokerfaced a smile.
I know there are people that stupid when it comes to matters of love at that age, but that was actually painful to read. This girl is straight up an idiot.