My problem with relationships

Sorry for the long message, I guess I need to share and to see if some aspects are evocative for others here.
As far back as I can remember, I've always had problems with relationships. My initial state as a child was one of weirdness I would say about social interactions - among other things. I've always had a much richer inner life than social life and initially I played with myself alone or I guess I thought that other children were interested by the same things as me but I was rebuffed - or more (bullied). But that's not really the aspect of the "problem" I want to tackle.
I've never managed to create by myself a friendship or true social links. In the past, up until my first years of studies, it has rather been others who came toward me and something could exist but I saw that I was not good to maintain it.
I am an introvert with a kind of underlying shyness. But over time I've seen that my problems with relationships were not really linked to normal introversion, that they were more peculiar.
When I was a teenager I read a lot about Asperger syndrome as it was called in the days or the conditions linked to the autistic spectrum but I could see that although I related much more to what was described in those books than to other materials, it was different from what I experienced. Although on some ways I guess I had a bit of a harder time than usual to internalize some social codes, my problems had different causes.
During my teenage years I felt quite different from my peers and I thought that once I would do my studies with people with the same intellectual or artistic interests, I would feel differently, more "included" in a group or on the same wavelength as the others. However, the truth was that I continued to feel "different" and to have exactly the same problems of solitude and loneliness. That is something that has existed when I was at university, as a student, then as a teacher and doctoral student and doctor and as a teacher in high school, in various environments, including in those where I would have had the most affinities to colleagues. Even in those, I was unable to build lasting links or social networks - and no relationships, no solid friendship.

It's true that I've got some problems that can be linked to my introversion. I have a kind of limited stock of social energy and these last years, my work as a teacher at high school (which is alas incompatible with my temperament) has taken its toll about that, limiting my energy for the rest of social life. I don't manage very well informal social events. Usually at an evening out with colleagues (for example) I feel rapidly alone and outside the subgroups and I dislike this feeling. In general I perceive well several social aspects but I miss out also quite a number of things. I am not focused on social life as a reflex: when I'm walking in the city, for example, I focus about things, buildings, atmosphere, rather than people.

However when I ponder about it I guess my problems come from something else. When I have an interesting and stimulating chat with a colleague, for example, I can find that stimulating and like the colleague in question, I can will to see that person again, but I don't really feel a drive or a pull toward it. But it seems that there is something that doesn't truly activate in my functioning about that kind of things. It seems to me that usually among people there are automatisms that regulate some part of the relationships and that in my case, they don't exist or are not activated.
I've read a bit about social anhedonia but it doesn't feel exactly like that. I can take pleasure in company and interactions. However I don't crystalize by myself those links and things stay at the same level with people. I don't have the mechanisms that self-propel friendship among other people, I guess.

My mind is much more focused on intellectual and artistic interests and pursuits than on persons although I can find them of course interesting (but often intimidating).
I've never fallen in love and I guess I have never had a truly profound friendship. I get well with my close relatives and I love them. However I am preoccupied by my seemingly incapacity to form more solid links. I feel quite lonely and alone sometimes and I wonder if it will stay the same. But I guess other people can "feel" that something is a bit "off" with me.
I'm trying to find sources and examples of that kind of situation in others to better understand myself.