I am that friend. I'm an INTJ personality, and I am terrible at maintaining friendships or relationships. I have to be reminded to call my mother. That is the sole reason I like Facebook, because I can leave a comment and there's my social interaction. I also have an aversion to the telephone, so no calls from me unless absolutely necessary. My sister is the same way.
It's not that I don't want to maintain the friendship or that I don't care about my friends, I just don't socialize well. I struggle to maintain a conversation, I often say the wrong thing or completely misunderstand what the other person is trying to say, and as awful as it may sound, I don't miss people, with very, very few exceptions. There are a few people I do miss, but largely I just don't miss people. I'm happy to see them or, more commonly, hear from them when I do.
My friends are either back home or scattered throughout the country. I have one friend in the state in which I currently live. It's largely a cultural thing, I prefer the company of intellectuals and productive people, i.e. artists, musicians, scientists, chefs, et cetera, and I live in a state where disability is a career path. Even without Asperger's I can't relate to the people here.
When it comes to close friends, the analogy I use is that instead of 100 pennies I have four quarters. The few close friends, my "inner circle" or "brain trust", all know, understand, and accept that I'm not one to initiate contact, and if I do it will be through snail mail, email or text message. The nice thing is that we can talk for the first time in six months and pick up right where we left off. It's not all one-sided, though. My "inner circle" has my loyalty and if they are in need of help, they will get it from me. They are the family I chose, and there is nothing I wouldn't do within the confines of the law for them if they are in need of help, advice, or just an ear to listen to them vent without judgment.
How do you handle friends like me? How much do you value their role in your life? Is it worth it to you to keep a friend like me around, or do you need people who are more reciprocal in their friendship? If the friendship takes from your time more than it contributes, it's probably not worth it.