Here's a sad story. I have a friend who is doing her research in developmental psychology. She works with little kids, preschool age, and one of the things she has to ask them is to nominate a best friend. She'll then check the answer from the kid who's been nominated to see if they'll reciprocate. This is pretty much how she defines best-friendship: reciprocity. She told me about this child who nominated more than ten names, none of whom nominated him in return.
Now I don't know about you, but I had this insecurity that I was that kid. I always had good friends, but there would be moments when I wonder if I'm as important to them as they are to me. Middle and high school were the probably the worst of it, as my friends made new friends and got boyfriends, and I found myself occasionally feeling like the extra, unnecessary wheels. In hindsight though, those whom I still call my best friends today were the ones who made an effort to make sure I didn't feel this way. So perhaps that period of growing up and apart was necessary, even if it made me wonder what was wrong with me.
I still get visited by that feeling, that wondering of 'oh, why don't you like me better?' when a friend on their way to being a close friend to me finds someone else and forgets about me. But I understand better now that sometimes it's a matter of match. As sad as it is sometimes, some people just aren't my kindred spirits, but that's okay. Now I know with more certainty who will nominate me right back if we were in that friendship study, and as long as I've got them, I'm all good.