ooh...that's a hard one. My dd was giving my dh a lot of trouble with bath and bed, but she was 12 months when that started, and it was because he was still doing everything for her, and she wanted to do things herself. So it's a whole different thing than what you have going.
I don't have any experience with your issue, but I do want to say that if DH could just remind himself that she's not targeting him, she doesn't mean anything by it. And maybe it would help him if he got a little extra affection from you instead, since he's feeling bad about dd.
Good luck, I hope some more people see this and can give you some help.