DP and I met 20 years ago whilst I was living overseas. Our DD was born in DP's country of birth and is now eighteen. I returned to the UK in 2008, we had some difficulty getting DP a visa but finally he got one and joined us in the UK two years later. He is now a British citizen.
Even after all these years, DP's language is still always 'we' (people from his home country) and 'you' (people from the UK). He has no British friends and says this is because English isn't his language so it's difficult. He has been in the same back-breaking job for years because he refuses all promotions as he would have to talk to the public and contractors and he doesn't want to because, again, he maintains he doesn't want to talk to people in English as it isn't his language. He spends his time at home voice messaging friends and relatives from his birth country in his first language and watching films from his birth country. He has always refused for me to have friends round to the house or to go and visit my friends and relatives as a couple, because he doesn't want to speak English.
I've often thought that he's depressed but he disagrees. He's not introverted in his birth country - we lived there together for some years and he talks to everyone and has loads of friends. He goes back for a visit every two years for a month.
Our entire relationship together over twenty years, and his relationship with our DD, has been in English, DD and I don't speak his first language, so it's untrue that speaking English is technically difficult for him.
Now we're getting older he's becoming even more entrenched in his ways. He only wants to talk to people in his birth country. He may not be depressed but he certainly doesn't appear happy. I don't know how to help him. Suggestions welcome.