Friends are not for ever, neither it is meant to be. It's perfectly alright, if you keep making new friends and there is no continuity. I had lots of friends, when I was in school. Now, I am in contact with only one of them. I had lot many friends in my colleges, there are only a few to whom I talk to nowadays. I had friends in my previous workplace, places where I used to stay before. At that time, it felt like this is it! We would make big plans together and all that. Then, priorities would change and you would move on and make new friends. That's how it is meant to be. Don't be hard upon yourself, it's perfectly normal.