On one hand, that's how you traumatise someone. On the other hand, she's such a combination of resilient, accepting, and dense that even that doesn't go through. On the third hand, she was already pre-traumatised, so it was a bad move for a reason he couldn't anticipate, rather than for the reason he should've.
For the rest of it, him scolding her because she's not telling him about things she really should is cute. It was a dumb move by her, although it is the kind of dumb move you'd expect from her.
He's also doing pretty much what characters have to do to get through to those who're as dense as the average harem protagonist.