I think they're just lust. Rosalie only liked him because he had curly hair like the baby she wanted and Emmett only likes Rosalie because she looks like a car model and they have wild sex. It says in the official companion that Rosalie was the type of girl he went after in his human life. He was a player kind of guy who slept with women and left them.

They disagree about everything, like Bella becoming a newborn, but they don't even discuss it. He doesn't talk to Rosalie about Bella and he doesn't talk to Bella about why Rosalie feels that way. It's like he doesn't are at all.

This was a very hard pick. I love their relationship but after Rosalie told her story to Bella in Eclipse I became a bit iffy. She said that Emmett reminded her of her friends' son and we all know by now that Rosalie wanted a child more than anything. Emmett was always childlike and immature so maybe in a way Emmett was the child she never had.

But then again, they broke houses (if you know what I mean winkidy wink wink). I may be thinking too much into it...