He has every right to feel upset, the conversation he overheard between her and her dad was so hurtful and easy to misunderstand (since he can't read her mind)... plus, he is already in a vulnerable state so it's normal for him to be this skeptical and defensive. And I think SHE is trying her best too, just because she remembers her first life doesn't mean she will behave and react perfectly the whole time... she's human and went through a lot of hardships