This is the sequel to this post. When do two people stop being friends? I like to compare this with the breakup of a romantic relationship: often, we remember the exact date of a breakup quite clearly. But sometimes friends tend to drift away from each other rather than having an abrupt “breakup.”
Friends drifting away may not have anything to do with ill will or bad feelings toward the other person; it’s just the normal course of life. You develop different interests, you spend time doing different things, and so on. So that person you were once very close to is relegated to the realm of “old friend”—they’re definitely not an enemy, and they don’t get demoted to the status of acquaintance because you did once share aspects of your life with them.
It sounds like a cliche, but I think that certain people are meant to be in your life at certain times for certain reasons. People who you were very close friends with but who drifted away some years ago may come back into your life, but their relationship with you will never be the same as it once was, and to try to make it the same is always futile.