I think he'd only pay her attention when using her as a trophy-wife to parade around the town + for when he wants children. But otherwise I think he'd be one of those deadbeat husbands that just ignores their wife.

^^^ and he would cheat

Agreed. She'd be well provided for and her father would probably be too and maybe he'd get more respect from the villagers with the most popular guy in town for a son in law, but that's all the benefits poor Belle would get. Gaston would get bored immediately since she's a bookworm and would probably try to hook up with the Bimbettes.

he seems the saddistic, so he would exploit Belle in whatever way he can.

Probably. He only wants to marry Belle as she's prettiest girl in village. He seems likely to be get bored easily with her, and probably cheats.

I have to find the video on this. There's a vid on youtube that goes into his character pretty deep and analyzes him. It was explained pretty well too.

I think he would do a bit of everything. I can imagine him trying to manipulate her emotionally to get what he wants too, although I don't think it would work.

I actually don't think he'd cheat on her at all, he seems thoroughly obsessed. But definitely ignore her whims and general happiness while doing whatever he wants.