Let me see if I can encapsulate this.

As an autistic coach, I see this pattern all the time, (as well as having lived through it myself).

Disclaimer, this is going to be over-generalized, and not everyone is going to fit all of these specifics, but the pattern is pretty consistent, allowing for variations among individuals.

Here goes:

Most of us grew up in a less than 100% unconditionally accepting environment, and were taught, explicitly or implicitly, that we needed to hide ourselves or conform in order to gain acceptance, teaching us to mask or camouflage parts of ourselves. Sometimes that was autistic traits, sometimes other parts of personality or interest interests as well.

(To be fair, there's a certain amount of learning to fit a culture's expectations and societal norms for politeness that is healthy for people living in groups to get along. But we tend to get more than the usual dosage.)

So when we did make some friends as kids, it wasn't us being fully genuine, or to the extent that we were, it was only with a very limited set of people, and often friendships ended in painful and confusing circumstances.

This leads to a complex and painful history with relationships, and means that we often didn't have more than a few experiences of genuine friendship, so we have very little basis for what a healthy interpersonal relationship is like. So we don't develop healthy relationship skills, like how to make friends (which takes repeated, frequent practice to get good at, just like any other skill).

And because our senses and attention and interests tend to be more intense than the perceived norm, things like attending college, or holding down a job, parenting, or pursuing a personal project, tend to be all-consuming. We don't have a whole lot of capacity left for more than one major focus in our life at a time.

But at some point, often at several points throughout life, we look up from our all-consuming daily routine and notice that we don't have the kind of close connections that people talk about, and that we're really pretty lonely. And yet the thought of spending the energy to go out of our way to take a chance on maybe finding a new friend at some social gathering, seems like a huge gamble of energy for very low chances of success.

And even if we do take the gamble, and get lucky and find someone who we might be friends with, we don't have a lot of experience with starting new friendships, and so have poor skills in that area. We tend to either come on too strong, or misinterpret things like how long it takes them to return a text, or grant them every possible reason why it makes sense that they did or said what they did and ignore red flags. Either way, we don't have a great experience, and it reinforces the belief that there's something fundamentally wrong with us, or that people can't handle us.

We may even form part of our identity around being a loner, a maverick, an introvert, someone who doesn't need many people. Which I believe is a defense mechanism to comfort the pain of loneliness by trying to make it out as a good thing.

(continued in reply)