>"Perking up" when another person's uncomfortable emotions come to the fore and steering the conversation away teaches them that their problems are their own, and that their full selves are excluded while a partial self (with unpleasantness filtered out) is welcome.

I suspect that the author meant this in non-intimate situations, however I agree with your general trend of reasoning. These types of people are comforting to the extreme, I would assume that would (technically) make them satisfying friends and lovers. I'd love to see a clarification of your use of unsatisfying here.