Fr. I expected him to just agree to letting her stay but saying she should talk to her sister for her mental state. I understand him thinking ill of her sister based on what’s he’s heard and wanting to not betray her trust by telling her to talk to her when she doesn’t want to, but it seems immature and not well thought out. If the police did get involved does he plan to hide it knowing that? What after that, etc.
He should’ve taken the fact that no one looked for her as a sign that it’s possible they could stay together and have the sister know about it if she was doing well and was safe.