I guess I'm one of those people that attract friends, I feel sometimes like I can't keep up with all of them. Life just gets in the way sometimes, it's not that I'm avoiding them or not keeping in touch, I do do that, I just don't always have time to do things with everyone. I feel a simple call or facebook message is good enough to keep a friendship going until time frees itself for a get together, and if someone can't understand that, then they weren't that good a friend in the first place.
When I graduated college a lot of friends moved away and I had to make new friends. I joined kickball, http://www.kickball.com
for anyone in the states, and made a ton of new friends there. I see them once or twice a week, and my other friends other nights a week. It's a great place for people to meet others or even get a date, because the solo thing isn't a deal, you hang out with your team. I had to change teams this season because my old team had too many players, and the new team was instantly welcoming. They got me into swing dancing and now I do that with them too. There's also a vegan on the team who is super cool and we have a lot in common. So yeah, kickball rocks.
I have had a few friends that were always like, hey, you should call me sometime, but never made effort to call me. People just say that as a conversation breaker I think, they don't really want to talk to me. I doubt they even have my number
So don't take it personally when people say that, odds are it's a cover so they don't seem like a jerk.
So far as real friends, I consider them all real friends. There are some that I talk about serious things with, and some I don't, not that I don't trust them, it's just that some people don't do serious well, which is ok. We can have fun hanging out without having to share our soul.