I lack one art that I wish I had. That of keeping in touch with folks.
I started using Facebook only after slacking for a while. Was not sure whether to jump in or not. And now although I use it quite regularly, I still ain't good at keeping in touch.
For different phases of life you end up choosing different folks to bond.
As kids, you are close to your school and neighborhood friends and to lota extend cousins, both paternal and maternal. Then you go to college and you bond with folks there (specially if you live in hostel). That phase of friends extend to a certain period till you get married.
For most part you still continue to be in touch, but it's not the same anymore. The dynamics changes a bit (whether you agree or don't) as it becomes us from I.It's just the nature of marriage. So, no pinning blame here.
Then of course your work friends join the inner circle and now your time and space is further divided.
Point here is simple, really. You "choose" your folks, based on your phase, situation and liking of course. This cycle probably continues till the end of your life, where you keep adding new friends, but then somehow also loose touch with old ones.
It's not bad really, if I am making it sound like it. It's really not.
You can stay in touch with only so many people all the time. It's practically impossible to sustain same level of rapport across ages, across phases and sometimes across countries / continents.
Things change. Situation changes... and again one ultra random stuff.