A long time ago I actually looked this up as to the behaviors of asd/npd/schizoaffective...as I was involved with an sza man for a while...a lot of behaviors he told me about, especially as a child pointed towards asd but his diagnosis as an adult went from bipolar 1 to sza/bipolar type. I just noticed the behaviors of those other 3 disorders are so similar and especially the way they affected me as a partner. He had several other disorders on top of the first and was a complicated man.
I am currently involved with a man I suspect is asd, I don't want to ask but there are a LOT of characteristics I see. I find our friendship to be difficult in ways but still I am trying to stick it out. I can't find it in myself to leave him for something he has no control over any more than I would want him to leave me for my bipolar disorder (which he doesn't know about yet either)
I'm not a professional in psychology or any of that, but have a lot of experience in facilitating support groups with people who have different mental issues and doing personal research on disorders that I was not familiar with so that I had an idea of what I was dealing with in the group members. I wanted to know whether a group member was showing symptoms of illness or was just being a jerk
I think there are a lot of symptom overlap/characteristic overlap with a lot of different mental issues...especially those that affect thought vs mood.