How did you meet OP?
TBH, the age factor wouldn't be so much of an issue for me as the distance. And that would be a deal-breaker. But for me, distance would have been something we talked about very early into the relationship, before even embarking on a relationship even, because there is IMO no point being in a relationship with someone who lives 3000 miles away if you know there is never any chance of a future.
It sounds as if you are settled here, he is settled there, and given changes in America now moving to be together is not going to be an easy ride. FWIW I do know people who have moved to/from America to be together, but even then it's not plain sailing. One couple I know are married as she came over on a fiancé visa, but even after marriage she still only has a three year visa to live here and then will have to apply for permanent residence. So even though she is currently living here, is married to her partner, there are still no guarantees that she'll be allowed to stay here in the long-term. Is that the kind of relationship you want? Living from visa to visa and always hoping for permanency?
And I'd second everything that @expatinscotland said. It's one thing to move to a country when you want to go and live there. It's quite another to move somewhere to marry someone you've only ever seen during holidays and good times, and not be able to try out living together because restrictions don't allow it.
It's hard enough living with someone for the first time even when you know each other well and have spent considerable time together. But moving in with someone when you have no friends, no family, no support network in the area and that person is the only reason you're there and it turns out you want to kill each other after a week because he doesn't take out his cups and leaves clothes all over the floor and you're insistent on the house being tidy is a whole different matter. You'll have no-one to vent to when you have your first argument. No friends to go out with for some time of your own. No support network if you have a baby. Having a baby is hard enough as it is, more so in a foreign country with no support network.
FWIW I am in a long distance relationship but he only lives three hours away. But four years in I've had enough of living apart and want us to live together. But I can't move from here because of my DS, and he can't move from there because he can't get work here. And now my DS has said he wants to stay in London when he goes to uni so my plans of potentially moving when he leaves school have just taken a hit as well. I have no intentions of leaving the relationship, but I do wonder whether I would have done things differently if I'd known then what I know now, and we're in the same country.
This is still early days for you OP. It's far better for you to end this relationship now than a couple of years down the line when you've exhausted all avenues of being together and are going to get your heart broken.
And for people who say that if you want it badly enough you can make it happen, that's simply not true. Life just doesn't always work like that.