SO and my stomach

When we first got together, my SO was obsessed with my stomach. Most guys are boob or butt guys, and he's a stomach guy. Now that I'm pregnant, mind you I'm 18 weeks and literally not showing at all nor have I gained weight (morning sickness is kicking my ass) he refuses to touch it. He literally won't even look at it. Anytime we have sex, my shirt always stays on, when that used to be the first thing he'd take off....
Is anybody else experiencing this? Where your SO doesn't find the same parts of you attractive?