Typed out a whole load then my phone died...
So he is in uni dorms - huge block with lots of small 'flats' (several self contained bedroom/bathroom) with a shared kitchen. The block common room is apparently always empty. It's very international, and yes, they do tend to hang together and speak their own language, but keen to mingle. But then I know he'd hate a noisy dorm!
I don't think he 'loves' his course but enjoys it from an intellectual level (he's doing well and gets on well with his lecturers). He says the other students are a bit geeky (hey it's a science course... what did he expect?) and not really sociable. One guy his dorm last year - he saw him once in the whole year (the guy never left his room - didn't go to class either).
I knew he was low last year - feeling like he hadn't found his tribe and a bit lonely.
When he was home over the summer we had lots of chats about realty Vs expectations (uni isn't all Animal House!) and that you have to make an effort to meet people, be relaxed, not to worry about not being alpha male/pack leader but to have some fun and join societies and clubs.
I also know he isn't much of a drinker - he doesn't like wine or spirits so I wonder if he had messaged his friend when he's had a few beers and got all maudlin. His friend is at another uni and I get the impression he has issues of his own to deal with.
Sadly he's like me - I'm introverted and shy - and find socialising absolutely painful and exhausting! I never addressed it and my parents pretended not to notice that I was very insular, but I just got on with it and it didn't bother me too much to be honest. Being shy sucks but it's a useful 'get out' to avoid people/things and I don't want him to be like this (I have tried really hard to explain this to him - don't be like me, this is what you need to do and I wish someone had told me this when I way young) - he's such a great lad, he really is.
I'm going to have a chat with him and try to tease it out of him. Of course I can't say that his friend spoke to me - going to have to pretend my 'mum senses' are tingling.