I've posted about this before, but I have a large circle of local friends and we do things together often. I was just with 4 of them at a sports bar last night watching the football game.

We've been friends for about 15 years and I met all of them through my boys. Most of my friends have children the same age as mine. But it hasn't always been that we could get together often, it's just none of us have little kids anymore so we are more free to do things together.
When our kids were little, we met once a week for coffee. I always brought stickers and paper for the kids to keep them busy while we chatted. It started with about 5 of us and as years went by, we added to it, and now there are 18 of us. We still call ourselves the "coffee group." (And I don't drink coffee.

)
I also have a smaller set of friends - there are 6 of us. We too have kids the same ages - I am the only one with kids still at home. For that group, we make it a point to celebrate our birthdays together. We even draw names every year for who gets to plan and execute the birthday celebration. And then we do a few more things together throughout the year.
It takes a lot of effort and planning to maintain friendships. I think it's important when you find a few people you might have common interests with, to set up a regular time to get together. Then it's not about someone being the first to call.
All that being said, I really only have 2 friends who love me unconditionally and that's my 2 sisters - who live 1300 miles away.