I have a bit more than "a little belly fat" and I feel self concious too. When standing, I can suck most of it in, but I obviously can't focus on it when sleeping. So, I hate it when I'm on top and I forget to hold it in, and then it starts to flap against HIS tight stomach. BUT, my boyfriend actually says he loves it. He says that he likes the way it feels in his hand, it's a nicer cushion for his head to rest on, ya know. My current boy friend is the first guy I've allowed myself to get close to, and him loving me no matter how I look at that moment, that day, or for awhile, has really helped my own self image. I feel sexy just being near him, and he can sense it and refuses to believe that it's really his own doing by him loving me no matter what.
The main issue: if your guy is OK with it, then forget about it and focus on more important things. :)