Where do you find Americans to socialize with, other than meetups with people on forums like this one? In the short time I've been in York, the only Americans I've ever seen are a few tourists who happened to be walking around the city center. I know that there are Americans living in York, but I suppose they are on another side of town somewhere, I haven't bumped into any.
I'm friendly with my fiance's family and friends, and I would like to join a book group or maybe some other type of group where I will meet my own friends, who I presume will mostly be English. And I expect to make some friends at work once I start working. So far, I've never had any English people treat me any differently because I'm American.
If I happen to meet some nice Americans, of course I'll try to be friends, but I don't plan on going out of my way to find a group of Americans to socialize with.