My husband has an adult diagnosis of high-functioning Autism. He was told at the time (and I whole heartedly agree) that he was diagnosed with the highest form only because he had managed into his 30s before being diagnosed, if they had figured it out earlier, then he would have been classified further along the spectrum.
You make a few really important points I would like to second. Sometimes I get motherly and really want to fix things for him, but he doesn't necessarily agree with my assessment. I am left with the choice of respecting or manipulating. It is SOOO incrediably important I never manipulate. That break in trust is something he has experienced his whole life and I have had to work so hard at establishing trust, it is not worth the relationship breakdown for me to take that initiative. To him, it is borderline unforgivable, even if my motivation is good.
When it comes to communication, this is a continual battle for us. He speaks too much (a defence mechanism I believe developed from people not taking the time to understand him), and I don't speak enough (he never feels like he understands what I'm thinking or feeling). I've had to learn that if he keeps revisiting a topic, it's because I haven't adequately conveyed something. It may be that further discussion is warranted so I do understand him, it may be that I do understand but haven't expressed this in a way that he is convinced, it may be that he doesn't understand why I'm doing or saying something. Whatever the scenario, patience is key on both sides to continue until it is resolved. Frustration that he is going round in circles, or "lecturing", is not helpful. I need to be asking more questions, or relaying back what he's saying in my own words to express my understanding, or I just need to be talking about me more so he comes to understand my perspective.
The other thing I'd add is that he is very intelligent and comes across "normal", so people very much underestimate the implication of that diagnosis in his practical life. It frustrates me so much when people think he can just do something different, change it, get over it, etc. it just isn't that simple for him, and he needs lots of understanding and patience. Problem solving is only really effective when he trusts that I'm not dismissing, judging or manipulating.
Thank you for raising this topic, it's very close to my heart.