Many of my once close friends in high school are now distant friends. I have some friends that only call me when they have a problem and I have other friends who randomly call me after not hearing from them for nearly a year. Things change the older you get and although some people stay in your life, some relationships change and become distant. People change and life's circumstances change and eventually you will find that new people may enter your life and you may end up having closer bonds with them. I think people come and go and help us learn and grow along the way. It is considered common, but maybe there is something you could do to mend the relationship.