That's not why she moved to the US though is it?
I think it's quite easy to see why someone would like Rosemary, she is smart and funny, she's confident, she obviously plays a big role in his kids life, she works within the confines of her visa whilst looking after their child. Sure she doesn't go to the gym and eats takeaway a lot but not being a size 8 isn't a crime and doesn't make you a 'slob'.
This may come as a shock but most grown ups pick their partners based on far more than whether or not they make a home cooked meal every night and go to the gym. And seeing that someone works and goes to the gym sometimes doesn't exactly say much about anyone at all does it? He's hardly going to be posting pics of himself panned out on the couch scratching his balls is he.