Sorry to hear that comrade.

I'm not sure about your circumstances but as general advice, especially to late diagnosed and late self-identifying folks, is that people who are autistic in particular form relationships in a different way from allistic folks (this also applies to a certain amount to ADHD folks but it tends to vary in degree) and to develop ways to embrace this.

If you are high masking and you put in a lot of effort trying to force yourself to fit the allistic mode of forming relationships then it's going to have some significant impacts on you (please don't take this as a beatdown btw, this comes from a place of sympathy and solidarity):

• You can find yourself putting in a ton of energy which can lead you to burning out and this alone can really disrupt efforts to have longer lasting connections with people if you're dropping off frequently or for long periods of time.

• Putting in a disproportionate amount of effort into a relationship by masking and trying to fit can lead to feeling unappreciated which can lead to you developing feelings of resentment as well as them being far less invested in the relationship, which can set you up for being abandoned and potentially even exploited or abused due to the inherent asymmetric nature of the relationship.

• You can find that all of that effort you put in means that the other person connects with a very "curated" personality that you have developed for them, rather than connecting with a more authentic version of yourself. This can lead to them feeling disconnected from you but moreso that you will feel unsatisfied and alienated in the relationship because they're not really connecting with you as a person but instead with a performance. And when that performance slips - when you need to be you - often people feel put off or deceived to see behind the mask and that can lead to them rejecting you. Also, on your side of things, when you have a connection to someone which is based on the curated version of yourself it's much more likely to feel superficial to you which makes it extremely difficult to feel genuinely connected and it becomes very easy to lose contact with people.

To elaborate a little more using an analogy, if you've ever worked in a customer-facing role then there were probably a couple of customers who you genuinely liked and looked forward to seeing, who you could be a bit more "human" with. Then there were probably the vast majority of customers you had that you felt largely indifferent to - ones who you would say the right things and put on the right smile with but you probably wouldn't even notice if they never came back through again.

That's a lot like how masking functions in a deeper sense with our relationships to others - if you're putting on something akin to a front that a customer service worker uses, you're going to come across a lot of people who seem nice enough but if you're only ever on that superficial level of connection then it's extremely easy for them to drift out of your life and for you to drift out of theirs without a second thought.

Also high maskers generally tend to have a high level of shame and social rejection, at least in their history, and this can be really corrosive to your sense of self-worth. ("Toxic" shame, if you want to use the modern lingo, but I'll spare you a dissertation on why I'm less than keen on that term because it's useful here as a conceptual distinction.) It's really difficult to form relationships when you are experiencing a high level of deep/chronic shame and low self-worth. If this is something that you deal with then neurodivergent affirming therapists and trauma therapists are going to be particularly important to help you work through this because, unfortunately, there's no simple bullet-point comment that can resolve this stuff as much as I wish it could.

With all of that said, I'd recommend that you seek out a setting where your niche interest(s) are likely to attract other neurodivergent folks. Think the nerdier stuff and the spaces which attract the diehard fans. It could be volunteering at a museum or it could be going to particular conventions or a local DnD group or a knitting circle. Whatever happens to be either something that you just love to be engrossed in or something that you could see yourself participating in which is likely to attract other neurodivergent folks to.

Generally speaking neurodivergent people are going to be easier to get along with, much easier to unmask around, and if you're like "Hey, sorry I haven't been in contact with you for the past 6 months" they're gonna be like "Eh, that's cool" or "Shit, has it been 6 months? I was supposed to have written my thesis by now and I haven't even started on it..." and you'll tend to pick back up right where you left off. (Of course neurodivergent people are people and that means you're guaranteed to find some duds too.)

Final thought: it might be worth hashing this one out with yourself or with a therapist but there's a big difference between being different/an oddball/whatever and in being an outsider. You can be a complete weirdo and still belong, even within a group of normal people. It's extremely easy to conflate your experiences of social rejection with being unconventional and to pin all the blame for the rejection you've experienced on that. The paradoxical thing in that situation is that the more you blame being unusual for social rejection, the harder you try to be normal to fit in and the more difficult it becomes, meaning that you can end up caught in a cycle that looks like:

Struggle to fit in > Get rejected > Blame being unusual > Try harder > Struggle to fit in even more > Get rejected

in an endless cycle.

If this is something that resonates with you and you feel like you want to work on it then I'd recommend finding a good narrative therapist for it because imo their practice model is much more compatible with neurodivergent people compared to something like CBT or, in this example, DBT and it's something that would be right up their alley.