I was talking to my friend Judy today, and FaceBook came up, and Judy said: "well, old friends are old friends for a reason".
I just loved that. Funny.
I love old friends, some of my best friends are old friends. But then some of them, while I still love them, these days we just don't have enough in common to keep the fire in an active ongoing friendship. Some people who have found me online after many years, it has turned out that we mailed happily back and forth for a couple of days, and then... I guess we didn't really had anymore to say, and it faded out.
If you no longer have at least a school or workplace throwing you together regularly, then you need a strong common interest to stimulate frequent communication, otherwise it just won't work.
Don't get me wrong, I love hearing from an old friend, and I sometimes wonder "what happened to...". Only I've stopped expecting that it will blossom into a lively, active friendship again, because that takes some kind of fuel.
Oh, and by the way (and perhaps "on the other hand"), some of my best friends are actually people I don't communicate with every day, or even every week. There are quite a few people with whom I feel I have such a strong bond and common reality that very frequent communication is not necessary at all. This includes people I knew before the web as well as people I met first time online.