In high school I had 30 casual friends and 15 close friends, at University I had 20 casual friends and 10 close friends, now I have 10 casual friends and 5 close friends, I predict them to reduce to zero when I get married. :(
Five years ago I had 20 casual friends and 2 close friends and then I met my wife. Now I have 60 casual friends and 3 close friends - including her. Getting married has been nothing but good for my social life.
I was at a huge high school, there were 55 alumnus per classroom, and 15 classrooms per generation, my friends at the University were a subset of the ones at high school.