i dont quite "get" why people say this is a dumbsterfire,
honestly it would be far more of a dumbsterfire if they went and got together imidiatly. yes, She is a terrible person for how she tried (and managed) to torment him, but nothing she did was actualy harmfull, baring the Cameras, thats... thats just messed up no excuses there, thats just fucked up and should not be romantizied in any way, like at all.
Everything else, while certainly wrong and definitly not healthy, can be indeed explained by the reason given, its not making it ok, and the MC forgiving her is indeed a REALY REALY boring way to end it
But at least she shows signs of knowing she is wrong, she tried to change at the end if only slightly, and the fact she is the one who says she cant forgive herself does mean something to me, a childhood trauma can lead you to do messed up things.
the fact she recognizes that she fucked up and isnt imidiatly going out with him is a good thing for me personaly. it shows she knows its wrong.