it’s easy to miss.
Really? I didn't think it was subtle at all. Even pretty early, when he drives her home and fails to tell her what he thinks about her, I found it pretty obvious that everything that happens to him is a consequence of his own actions. At this point it can still be excused by him being insecure but as soon as he uses the willow, it is very clear that he doesn't care even a tiny bit about what she wants, he just wants to own her.