@Setanta,
A lot of interesting points made here.
I've had a very self involved friend like that, one an early best friend in my high school and college years. It was a treat for me to have a friend to pal around with, especially in the high school time when I lived fairly far from school, was new to the city, and then worked after school. It took me quite a while to figure out how one sided everything was, and longer to do anything about it. Some natural distancing occurred as we grew into our twenties, but it was still the same when I saw her every once in a while. I eventually told her, with the new perspective, my thoughts on our friendship, and she was quietly defensive, the idea being new to her. That's my fault, in that I had let the dynamic develop over years, or "enabled", as they say.
She called me here about a year ago. I nearly plotzed. The exact last person I wanted to hear from, if I had had a prior thought about such a call. She had no apparent recall of any strained last conversation, but had some sharp words about my not keeping in touch. We talked a while, some of it even about me as by now she was curious. I took her phone number, won't be calling.
I realize that she thought we had a fine friendship back then, important enough to her to look me up in later life. But.. since then I've had some really good friends, whether or not any of them or I became self centered for a period of time. I also look back and see my interest in getting along made me abnormally quiet with this high school friend, or people like her. Or kept me quiet, as I was something of a quiet kid. So, to some extent, she filled a need for me, to have a friend - I did get something out of even the one sided thing.