I'll add my own data point into the mix. I'm 49, have been married for 22 years, with kids who are either grown up, or well on their way. Throughout my life though, I have been an absolute loner in spirit. I grew up quite isolated, in the UK countryside, and learned to amuse myself early on. My first love was computers, which luckily has served me fairly well, career-wise. I haven't had many girlfriends, and felt ver…
I haven't had many girlfriends either, but I haven't felt that as a "lack". I've never had many friends either - usually not more than three or four good friends at any time.
I now live alone, and I don't see many people. I talk to my exes fairly regularly, and I'm on good terms with my kids - but they live faraway. I'm not "lonely", though, in the sense that being alone makes me sad or regretful. I'm fine with my own company. I like to crack jokes and talk politics, so I miss those occasions; I miss cuddling a warm woman; and I'd like to have someone living with me, to pick me up if I fall over, and to look after me if I get ill. But those things are basically transactional, not about loneliness; I could pay someone to provide those services.
I'm not a "loner" - I like people, and people like me. I'm not shy. I think it's just that I find that cultivating casual friendships in the hope they might blossom is a lot of work, so I don't cultivate many. And the idea of having two girlfriend relationships at the same time - i.e. while one is ending and the other beginning - fills me with dread, and I've never done that.
Like you, I've spent my career in IT. I've never made a good friend at work. I mean, I've made "friends" with people at work, and even brought them to my home and made dinner for them; but they were never good friends. I'm a bit idiosyncratic in my tastes, and many of my attitudes and opinions are quite leftfield. These work-friends were all very straight, by my standards. I've no objection to people being "normal" - by definition, the majority of people are - that's no obstacle to being friends, for me. But it may have been an obstacle for them.