The self only exists in the now. Human relationships affirm this existence of the self, which we seek to continue indefinitely. The closer the relationship, the more it affirms. Thus, why we experience such tragedy at a loss is because we lose that affirmation that we ARE something. We have innate desires to continue believing in the self and these are what latch on to others in an attempt to validate itself. Without these relationships, the self has little structure to support itself with, because the structure has nothing but itself to brace itself up against the inevitable realization that the self doesn’t exist. Interaction with others is a continual, necessary distraction for most people, especially those who have little internal supporting structure to keep the ego going.
People who reject human interaction are seen as unsociable because the rejected come to realize their own weakness at egoism or self validation. They want to rely upon and be relied upon, but when they’re not they see the denier as less human. Once the perpetual, universal system based on reliance upon others is set up, the easiest thing to do is to go along with it. But when you don’t, the system rejects you.
I don’t feel rejected though, it’s just a thought. Pretty easy to fit in and give and take a little.