I think this is it. Many people, regardless of age, just want to be left alone for whatever reason. It's nothing personal. But, as you age it's true you become set in your ways and don't want to bother with someone too different from you. My mom was a social butterfly, and when she went to assisted living I noticed none of the residents hung around together, went to each other's rooms, or conversed much. They played games and did crafts together but no one seemed to be friends. It was odd.