aww this is a little sad: knowing and believing you're being fooled but pretending to fall for it just to make the other person happy and to keep them by your side....thank god she isn't really fooling him and they'll be happy!
Also, who blames him? From her past life, she obviously never approached him or loved him so he has every right to not belive she will change over night. Maybe she shouldn't have done a 180 degree change all of a sudden ? Maybe take time to pretend to be sad over the asshole and then gradually start showing the ML her tender side instead of what she did