>>/113909/
Asociality is not normalcy, you're conflating your personal sphere with the experience of men at large. Everyone has a group of friends and a social context (school, job, hobby) where they can find new people. Men who have a girlfriend get to know many other girls through her, this is why people who have been in relationships have no issues finding new ones and lonely people only tend to get lonelier.
Social opportunities only start to decline once you reach the age bracket where everyone has kids.