DS has just turned 21 and is at uni. All his life he's been a rather solitary person by nature. This seemed to be partly his own choice and partly that he just "didn't know what to say" if he wanted to talk to people. When he was about 6 I asked the school nurse, during a health check, whether she thought he might be mildly autistic and what I should do if he was, and she said that it was possible, although she didn't really see signs of it, but as he was happy as he was, and doing very well academically, she wouldn't advise doing anything.
Until his mid teens he usually had one or two closeish friends at any one time, usually people who were similarly a bit quirky/nerdy, but he hasn't had much of a social life since it stopped being about parents organising tea invitations and started being more about the kids themselves informally suggesting something. He always said he did talk to people at school but mostly about the work. He tagged along sometimes if people were going to McDonalds or something at lunchtime but I don't think he ever pro-actively suggested anything like that. In his first year at uni he lived in a flat in hall and hung out with his flatmates quite a lot in the first few weeks, but as the others developed new friendships on their courses, this gradually fizzled out. He still occasionally played pool with one of the other quieter ones and went to his subject-based club every week, but that was about it. He seemed happy enough like that, but if I asked him if he'd ever tried to get talking to other people, he'd just say "I don't know what to say."
The second year was difficult for him and I think it knocked his confidence a bit. He left it too late to find a group of people he already knew to look for a house with, and ended up moving into an established house where he was the only new person. Two of them did make some effort to include him at first - they invited him to go somewhere quite interesting with them - but I think they lost interest when he didn't reciprocate with an invitation of his own. He was also quite unhappy because the others didn't clean after themselves and were very noisy, and he found it very hard to confront them about it, though he did say something to the landlady in the end and she sorted it out. But basically he became more and more isolated that year, never really becoming close to anyone in the house and only talking to his coursemates about the work. He had quite a tough workload and stayed in a lot, trying to keep on top of it.
Now it's his final year. Again he's living in a shared house where he didn't know the people before. He's happier in this one because they're more considerate about noise, mess etc, but he hasn't got to know any of them at all well (there are quite a lot of them and he still doesn't know what some of them are called, and thinks it would be embarrassing to ask now). Again he's had to work very hard, and while he doesn't always enjoy that, I think it's the only thing that stops him seeing how boring his life is because he doesn't socialise. If I ask him why he doesn't just strike up a conversation with someone on his course, it's the same old excuse - he doesn't know what to say. (He talks to people he's working on projects with, and to his lecturers, and can handle "administrative" conversations just fine.)
Also, he never seems to feel any strong emotions or have strong opinions about anything, with the possible exception of getting a bit panicky about work deadlines sometimes. If he seems interested in something, he tends to lose interest if people start assuming he's interested in it and trying to get him to participate in it more.
My gut feeling is that he isn't autistic, because he doesn't seem to fit all the diagnostic criteria - he's never had any obsessions that I know of, doesn't fear change (in fact as a child and teenager he often moaned about eating the same things or going to the same places what he felt was a boring amount of times), never has anything resembling meltdowns, doesn't seem to have any sensory issues - he just doesn't like communicating! I wonder if he's somehow just got out of practice because, as a natural introvert, he didn't see the point, but could relearn some social skills if he was prepared to put in some effort. But he probably feels that keeping on top of his work is the biggest priority and he can't afford to take his eye off that goal. He doesn't even enjoy his subject all that much any more, by the way, but agrees that at this stage it's probably best to keep going, get his degree and then think about what he wants to do next.
Any thoughts on what might be going on here - does he sound autistic to you? Depressed? Social anxiety? Just an introvert? If he ever decides to help himself, what would be the best thing for him to do? I recognise that as an adult he has to make his own decisions about any course of action but if he comes to the point where he sees something needs doing and asks, what do I suggest? I sort of feel that life will only get harder for him once he gets a job and doesn't have any inbuilt social "scene" around him, whether he chooses to participate in it or not.