The thing is, that when you're young, you always think you'll meet all sorts of wonderful people, that drifting apart and losing friends is natural. You don't worry, at first, about the friends you leave behind. But as you get older, it gets harder to build friendships. Too many defenses, too little opportunity. You get busy. And by the time you realize that you've lost the dearest best friend you've ever had, years have gone by and you're mature enough to be embarrassed by your attitude and, frankly, by your arrogance.