Please understand that this is what these relationships do to you. They are incredibly adept at making you question yourself.
I remember when I first started going out with my ex, I thought he was amazing and I fell in love very fast. Then he wanted to move in with me and I was over the moon.
Then valentines day came and I started talking about "where should we go on Valentines day what do you think" - his response? "I don't do valentines day, I don't like celebrating it and I think people who celebrate it are sad, I feel sorry for all those couples in restaurants sat there for the sake of it".
Well, I was taken aback, but naturally I thought well that's ok, so I started suggesting other things like going out for a meal on another day, or cooking something special at home. It didn't even occur to me that his attitude was utterly ridiculous and that I disagreed with it because I was in love and he was probably right anyway I thought.
Plus, in no way did I want to be "like all women" which is what he would say about "womens expectations". No way, I was going to be the cool girl, the one who didn't have any expectations like those OTHER women, I wasn't going to be like them. I was different.
Not long after that I started to get sad about his lack of affection, the fact he didn't seem to really want to snuggle up with me, he always felt stifled by me, yet he would sit and hug his dog in front of me while I was at the other end of the sofa. I brought it up with him and was told that he wasn't going to "fawn over me constantly". I assumed he was right and I was being too needy and felt sad and unreasonable.
On and on this went for years and years and even a pat on the head would make me the happiest person in the world. Being told I looked nice would have me made up for the whole day, not that it ever happened often!
Yup, I had the discussions about going overseas as well, and I was so happy when he gave me a PRINT OUT of a holiday we "would go on" for my birthday. So essentially he gave me a piece of paper for my birthday. He said that we'd go, then covid happened and I never heard a single word about that holiday ever again even after covid was over. Admittedly we'd bought a house by then but honestly, I am pretty sure it would never have come up again regardless...
My point is that this is what happens and you end up feeling completely like you don't know if you're right or wrong. The simple answer is what do YOU really think? You clearly think that this is not what you want, you have clearly been finding reasons and excuses for why you should tolerate it or why it maybe ok and my advice to you is please stop doing that - he's doing what suits him regardless of whether he's just an asshole or whether he had a lobotomy at 2 years old that you didn't know about - it doesn't matter what the reason is, what matters is your unhappiness and the fact that life is finite. You don't get a do over when you waste time with people like this, you get to carry on feeling miserable if you stay then die miserable, or you can decide nah.... I'm not up for this anymore and whilst I might miss you and be heartbroken, there is now room for something different.
Just know this: People like this do not change, and if he's autistic and that's the excuse you're using, it certainly won't change ever. Pick your poison on this one basically.