Oh, she just developed amnesia just after she f-ing dumped him and is jealous cause theres a new girl and she can't object as much as she can because of her own retarded scheme?
My my, how convenie- I mean, unfortunate. If the MC is also a dumbass and even though he's supposedly a "genius actor" he won't be able to see through her bs, this would most definitely score her sympathy points!