She has explained that if a conversation is intense or emotional, eye contact makes it hard for her to focus on what is being said. She usually needs something to fidget with in these situations, too. I am okay with this for now, as long as I feel she is still attending to me. But in casual conversation, there seems to be something else going on. She is highly visual/artistic/detail-oriented, and gives that as a reason ("I like to look around and notice things"). I don't know if it's really that, which sounds ADHD, or if it's discomfort-- more on the ASD side.
I have definitely talked with her about the messages body language sends. The irony is that if I pose for her, or give her little online social-skills cards/scenarios to look at, she can "read" them and pass them just fine. She can say, "Yeah, if you do that you look like you're listening, and if you do that you looks like you don't care." But if I ASK her, "Do YOU personally care or notice if someone doesn't look at you when you talk?", she's like "Mennh...not unless it's really extreme and I can tell they're not paying attention." She has a surface understanding of what is expected but is not bought in.
