Making friends on this forum

This is a genuine curiosity I have. I've noticed from some posts and replies I've read that it sounds like some people here are friends with each other - I'm not sure what that means exactly, but let's say at least that those people seem to communicate with each other on a regular basis, maybe it means more. My question is how did these develop? When I consider the stages of making friends, in my life it seems to go:

1. Meeting someone new, have basic conversations with them
2. ??? (Something happens here which I don't understand)
3. I now have a friend

So I always seem perpetually stuck at steps 1 and 3. I'm interested in other people's experiences.