If he is athletic and it's a sports oriented school he may well have a good time and be popular. You can provide support letters, e-mails, and maybe the odd weekend break if his mother permits. Sounds to me like his mother is investing all her emotional energy into him and it might be good for both of them. She can still give him all her love and attention during the holidays unless of course he ends up going away with new friends, school sports tours, (friends son ended up going to play cricket in Sri Lanka for three weeks)