Realised my Sentiment I've been mulling is a little different. The idea is basically: communication is "important" in relationships in the same way that, say, subatomic particles are important to matter, or brushstrokes to a painting. Meaning, if you look close enough, actually the whole thing consists entirely of acts of communication.
From the D-est of MCs down to the slightest glance - even the fact that you choose to interact with that person at all, on a material level, the actions that take place are all acts of communication. After all, you wouldn't do any of that if you didn't think they would notice, or respond in some revealing way. Hell, the entire difference between masturbation and sex is the continual back and forth broadcasting of consent, desire, affection and so on. Communication is not "important" for the relationship, it is the relationship
But this model is obviously not complete. Well, it wasn't supposed to be! It's a materialistic view. But maybe it can be part of a larger model. It captures the act, but there's some sort of psychological substance it doesn't account for. There's an object, a construction, that lives in each participant's head, that these acts of communication build and maintain. But what is it made out of? What is the substance? What exactly is it that you're communicating in the first place?
"Needs, boundaries and hopes", as you've described, is a strong candidate for the answer to that question.
