Being alone usually means you do something alone or spending time while alone which is good unles you really are lonely. I’m personally almost never alone so I don’t know anything about that but there are many people who don’t have friends or anyone (relatives or something) spending time with.
There can be also lonelines which comes suddenly with a new life situation like it happened to one man I know. It must be the worst. First years and years there was everyday trafic and then nothing. Totally silence.
Imagine this: for years the nurses came 2-3 times a day to helping his old paralyzed mom (”A”) and then I was there every weekday (as a care taker (or as a personal assistant)). There was people always. There was ”A’s” son’s lively dog (which lives still there). There was life…and often even chaos. Then ”A” passed away and that life disappeared just like that. There was no one anymore around him. Imagine that. He must really felt lonely!
On the other hand he have now that time he always missed. That time to study…time to do what ever he likes. No one will interrupt that (cause no one will need his help). The good thing is his an introvert who have always enjoyed his own space and I think in time he will adapt better than maybe some others would…but it surely takes some time.