He has done it though and that's a scar she will have to live with for the rest of her life. Going by what's happening now I honestly don't think he is the best choice or someone she should be associating with period since it's doing psychological harm to her. When she gets over it if she ever does then fine let's forgive but it's still way too early. He's still a cocky lol asshole I'll be fair and say that now he's trying to change but still let's see how it goes and if he changes that cockiness. At least he doesn't really say anything horrible about her now and plus we don't even know how he will act when that damn chick from the future comes. There's a possibility that he's gonna turn right back into an AHole. For now.though it's a "let's wait and see"
The him now and the him then are not the same person. Depending on circumstances and different events, people change, for better or for worse. That future him fucking sucked ass, but since the past has been changed, that person doesn't exist anymore, which is what the author wants to show. Don't hold a kid accountable for something he technically hasn't done.