I feel like we should cut her some slack, how long has it been since she found everything out? And let's be honest, his appearance is not the only problem, his attitude is the main one. He wants to be seen as a man, yet he behaves like a kid. Even in this situation, he could've said her that it hurts him that she sees him that way. But what do we see? His typical behavior from the first chapters, he hasn't changed, and it's been years.
I thought that he would've become more mature through the series, but he's still the same.
She is wrong to treat him like a kid, but she's still overwhelmed by the whole situation, even if she knows he's not the same, she can't accept it right away. And he is of all people should understand that, bc he's gone through even more serious experience.