As you grow up, some friends you will grow closer to, and some friends you will distance yourself from. It's a pretty natural process, so I wouldn't feel like it's "your fault" or anything like that.

I was best friends with this person for like 3 years, then in a matter of a few months I started hanging out with a different crowd and now I rarely even see him anymore. Sometimes, the nostalgia of 'good times had' can be overwhelming, but looking back I don't think I'd have changed anything. Interpersonal relationships aren't always meant to last, and that's just life.

Yeah it's natural to drift away. Personally I stick to my friends like glue though. Unless it's clear they don't like me of course.
The only way I'd say you were cold-hearted is if you ignored them completely and act like you were never friends. I hate it when that happens.

It's called growing up C:

Perhaps you should at least try getting to know at least one of the few, rather than turning a cold shoulder. You never quite know when you'll need a friend.

exactly, the more people who have as 'friends', whether that is the closest of relationships or casual acquaintances, the better. if u have some form of relationship with alot of people, you will be better off. as for you not clicking with your friends, that is normal as your getting older.

cold hearted friends are the best, they toughen you up and prepare you for the harsh reality of the world

what an optimist and generally positive person!

As people have already said, you grow up and drift away from some of your friends, it's just natural.