Tips for supporting autistic partner

I have autism, but I also have a very hard time expressing my needs. Recently, I’ve been having a lot of rumination issues and my partner has a hard time breaking me out of it without making me feel dismissed or challenged, and in return it inflames the whole situation because he feels then like we are fighting. I’ve been trying to find articles on how to support an autistic partner, but I can’t find anything except for stuff about children, or it’s basically just “defining” the issue but there’s no information on how to deal with it as the carer or partner. I’m a late diagnosed autistic person and up to this point in my life the people around me have just “known” how to deal with it so I don’t even know what to say when he asks what he should do because everyone else has just done it.

I don’t know how to verbalize what I need and I can’t find any articles that are helpful enough to send to him. What are the kinds of things that you’ve told your partners that are helpful for things as small as planning food and as big as calming down during a meltdown/argument? Any advice is welcome.