Just an FYI, the University of Washington has a lot of resources on self diagnosis and is validating resources for self diagnosis for Autism (particularly since adult assessment is so inaccessible). Also embrace-autism.org is a nonprofit in Canada that is studying and helps with self diagnosis resources for Autism, and it's run by Autistic researchers.

As CANDC mentioned, you cannot diagnose her, but self diagnosis is widely accepted by the Autism community due to the lack of accessible resources. Looking at some of the self assessments and screeners may help your wife if SHE is interested in learning more about it. But again, they are self assessments, not for a 3rd party to fill out for her.

And, in terms of the relationship, addressing the actual problems might be the way to go versus pinning those issues on one thing or another. If there is a communication issue then it's about understanding the issue and how you each communicate individually and learning to communicate with each other. Now if one of you is Autistic and one is Allistic, that can impact the communication, but the solution is still the same - talk about how you communicate differently and accommodate each other so you can understand each other.

Hope this helps.