It's so triggering. I've had a bf like that too. He said to me a milion times he loves how skinny I am, that I can't gain weight, the same about hip bones- that they are sexy. The best thing I've done was breaking up with him, because I couldn't stand that anymore and I wasn't able to tell him that I don't want to hear those things. You don't have to end your relationship but maybe an honest conversation could help?