I think lack of ToM (Theory of Mind) has a lot to do with poor interpersonal communication.
I'd be surprised if "contemptuousness" has anything to do with it.
Interpersonal relationships are very difficult for some of us.
This is all connected of course, but I'd suggest there's a bit more to it:
* People with a different "emotional palette" than NT norms, and/or less intense emotions (both would categorize under Alexithymia) don't have the same body of experience as a "standard issue NT", and even less so an NT who self-classifies as "emotional"
* People who think more visually, or even more difficult, neither verbally nor visually, have a harder time communication about their emotional states even if they are "100% typical" in terms of their feelings.
It's
much harder to discuss something abstract when there's no shared vocabulary
* Then you have the 100% natural, evolved M/F bias: (a) Men frame things as "problems to solve" what women frame as "a topic for analysis and discussion"; (b) Men regulate their emotions more actively, and are inclined to wait out imbalances rather that talk them out.
(NB: this is part of the "Hunter vs Gatherer" split of you look at it with an evolutionary lens: whatever someone feels while in the middle of a fight with a hungry Smilodon is best deferred
Except for goal-directed adrenaline-fueled rage OFC, but I don't classify that as an emotion at all. YMMV.
* ToM belongs on the list OFC,
What it all nets out to is that some 100% reasonable people won't be able to talk about their own emotional states, nor discuss someone else's emotional states with them.
In a "relationship", this could be negotiable, a low-level problem, or a show-stopper, depending on circumstances.
Uncertainly
should be handled via clear and honest communication, leading to a negotiated result.
But people are people - that's easy to say in a forum, harder to actually do it IRL