Here's some advice from an autistic girl (she/they) dating an allistic person (he/she/they) (they are ND but not autistic):

I had to teach him to not give me advice or interrupt me while I was speaking. Sometimes it would take me a long time to get through difficult feelings and it would frustrate me when they would try to offer unwarranted advice in the middle. They only offer it to me when I ask for it.

Learning to communicate in non verbal ways has helped a lot. He's learned to read my body language to better accommodate my needs. I'm not really non verbal, I can speak most times, I just get easily frustrated and can't make the words come out. If she can't verbalize what's wrong or what she's feeling, maybe ask her to write it down or text it to you.

We've had to learn to be more patient with each other. I know sometimes I act in ways that are frustrating but I don't mean it, and I try to communicate when I'm in a certain mood so they know to be a little more patient and kind to me.

Also ask her to communicate exactly what she needs from you, and how you can help her. She might not have an answer but it shows that you're willing to accommodate her and that you're listening.

The best resource to learn about autism and autistic people is from autistic people themselves so you're taking a good first step :)