I've been with my ND partner for 30 years.
Lectures, special interests, stimming, other people including me simply being wrong, meltdowns etc have been part of our lives.
As have creativity, articulacy, great conversations, pretty much perfectly aligned shared interests and activities, art, drama, writing and friends.
'High functioning' can be a euphemism for 'high masking'.
You've just spent 10 days together, the longest time. For him, keeping up the social masking and portraying the 'high functioning' character everyone else sees is utterly exhausting. He's relaxed it. He feels safe to, with you. And now you're seeing the real him.
He has a brain-difference disability. Just as a person who is blind or has a stoma bag has a disability.
His happens to be a genetic difficulty around communication and appreciating other people have a different word view and opinion and that this isn't necessarily wrong - but it upsets him, so he feels a need to put the wrong thing right.
This is a complete package, along with the stuff (I assume?) you like, love, respect, fancy, etc.
Question is, could you do 30+ years of it?
He will age, he will perhaps mellow and learn.
But he won't get any less neurodiverse.
And if you do have children ... be prepared to be 'wrong' about your pregnancy, labour, feeding, upbringing etc etc etc choices.
If you're to continue together, you're going to need to educate yourself about the reality of living with a ND man. Because as the presumably NT person, changing, adapting your world view etc is going to come more readily to you than to him.
Can you do that?