Some people enjoy solitude. I enjoy friends and some socializing, but I don't have a desire to befriend people. Casual contact suits me fine. I'm a person who needs quiet.

It can be an aspect of the Schizoaffective Personality, which is not psychotic although the name sounds like it. It exists on a continuum and I think the degree to which we want to have others in our lives is related to where on the continuum we lie.