Help understanding my partners intimacy issue


I am posting this in desperation because I cannot find anything like it on the internet and I want to try and find some hope, somewhere, that our relationship isn't dead in the water.

I've been dating someone for a while now who I care about very deeply and can even see a future with, but they are unable to be intimate due to severe negative feelings (the word "dirty" has been used) after the event occurs. They're fine with cuddling and hugs but kissing or anything sexual triggers it. Has anyone else experienced this? Is there any way to deal with it or mitigate it? They are currently waiting for a diagnosis but presumed by themselves and those who know them to be somewhere on the spectrum. Most things I can be patient and caring and accept but this one is just too much of a challenge. I don't want to lose them, they're an amazing person.

Am I being stupid to think that this could ever change?