Like the second poster, you couldn't pay me to move to the US. I'm not very fond of the idea of living in the Middle East or deep in a tropical jungle either.
There was a poster in Relationships a couple of days ago who emigrated to Australia with her boyfriend, and now she was stuck at home, unable to work and he wouldn't share any money with her, so her life was just buying and cooking his meals and washing his clothes.
There are a million similar stories.
You could end up trapped out there, unable to work, reliant on him and hoping he doesn't leave you, because then you'd be single, unable to work, with the kids you can't bring to the UK nor can you leave the country.
The education system is pretty poor. If you go private it's often a religious school. In the red states, they're suspicious of atheists (amongst other things) but life in the blue states might be OK. Ish.
It's the inability to work that strikes me as the biggest risk. You might love America but one phonecall from your loving boyfriend could see you deported, one day he wakes up and decides he's not 'wasting' money on you anymore and you have nothing. People can turn mean. Especially when they think you cannot run.