@les24preludes We're a friendly people, but can be reluctant to form friendships. If it's any consolation, even Irish people find it hard to break in to a new social circle if they move somewhere else. We are gregarious and helpful to strangers, but getting closer than that requires a surprising amount of work. I don't know if there is one in your son's case, but a language barrier makes it harder, as the way we use English can be confusing to non-native speakers - or native speakers too! I've seen American co-workers getting thrown by things that we think have an obvious, clear meaning.
I've been on the other side of this, by the way, so I do understand: as an immigrant in another country, I found I had more in common with other foreigners, as we had a shared experience of being baffled by the native population.