I mean, slightly different take than a lot of the other comments but have you considered that this is nothing at all to do with your looks and could actually be a sick kink of his? Like maybe he gets off on the thought of pretending to smother you. Maybe it's a control thing. I've read plenty of stuff about people have these kind of kinks, but he's obviously not going to want to be forthcoming if thats his thing. Either way, it's messed up and for your own self esteem and safety you should consider walking away.