I assume you are referring to his behaviour at Upper Cross? I agree with Deborah that his behaviour is not that bad. In fact, as I posted before, it is possible to argue that on the morning of their first meeting he has gone to some lengths to mitigate what is, at the very least, going to be awkward for her. It seems to me that beyond that he mostly does not know how to behave towards her and so falls back on 'cold civility'.

Intention is important here. If his anger was leading him to be outright rude to her then I would agree with you. But he must be remaining within the bounds of socially acceptable behaviour or even the self obsessed Musgroves might notice and his sister certainly would. The fact that it hurts Anne to be treated thus probably more than actual rudeness would is nothing to the purpose - he does not know what she is feeling. He is not in her head, like we are (and he is not Mr Knightley with that gentleman's sophisticated understanding of gender relations, and warm sympathy with most of the women in his life!)

What I think he is doing wrong is staying at Kellynch. If he spent two minutes rational thought on it, he would see that staying in his ex-fiancee's home and wooing one of her sisters in law is bonkers. He should have moved on smartly. But he doesn't because he is not thinking rationally, he hurts Anne because he does not know how else to behave with her, and he nearly ends up having to marry Louisa because he does not watch what he is doing.