I am not sure if this applies to everyone, but it happened to me. I lived alone for over 6 years in a city where it was almost impossible to make friends. Sometimes I felt lonely, but sometimes I really enjoyed being alone. What happened later is that when I started living with people again, I sometimes felt that I wasn't very comfortable with so many people around because I kind of lost that space I had before. When I was living on my own, I had a cat to keep me company. I know that cats can't talk to you, but it helps somehow.