Friends Throughout Life: Childhood, College, and Adult
There are many types of friends you will meet (and lose) in your life. People change as they get older, and the types of relationships they have change too. These changes may take place passively, as friends just drift apart due to no ill-will on anyone's part, or explosively in the form of irreconcilable arguments. Childhood friendships that last through college and into adulthood are especially rare (that is to say close friendships, not that being Facebook friends with former classmates doesn't mean anything at all). At every stage in life's journey, we meet new people and make friends with them; whether or not they'll last only time will tell.
I've always longed for that ideal childhood friendship of two people going through the trials and tribulations of growing up together. Alas, pair-bonding in this way just wasn't a long-term possibility in my experience. Children tend to go through phases and friends quite rapidly, and those who can't keep up are either kicked to the curb or left by the wayside. It's no one's fault, really, except that children are prone to mistakes and not knowing when they've made them. They may not know how to effectively deal with problems, which may be more complex than their parents realize and can't advise them on. Even after-school specials may not help (as one abridged series writer put it, "I can't believe those cartoons lied to me!"). Ultimately it all comes down to figuring out who you are and surrounding yourself with people who will accept you nigh-unconditionally like family.
While many people enter college with their own group of friends (which will be a different group than at any point in time in their childhood), that group will be entirely different upon leaving it. Again, this is usually no one's fault. Old enough to know better but maybe not what you want out of life, this is a common jumping-off point for people to go their own separate ways no matter how much you planned on sticking together. When people talk about the business they planned to open with their friends in their first year of college, I just have to laugh good-naturedly and also a bit sadly because it's probably not going to happen that way, if at all. It's a nice plan, and there's no reason why it shouldn't happen, but life gets in the way, and other things end up happening instead. Anyway, you will meet new people in classes and clubs who share your interests perhaps more so than anyone back home ever did (in that way it's like having pen pals over the Internet, as you have to go a long way to find them). However, these may not be meant to last either, especially if you have roommates.
Then there are the friends you make later in life after you have become settled in a stable relationship and occupation. These relationships are different from the previous two, as you do not share a history of any kind with these people. As such, they are seeing you as what you are now and not what you were. In a way, it's like moving to an entirely new part of the country and starting over as someone else. Unless you are able to form a strong emotional bond with these new adult friends, it will only become another casual friendship, which is fine if that's the lifestyle you've decided to follow. It all depends on how your life is structured at that point and what it revolves around (kids, business, etc.). If you still have friends from college and your childhood, that's great too. As adults, your relationship may have changed a little but not enough to want to part ways; you make it work. To that I say "Congratulations!"
To conclude, friendship is a labor of love at any stage in life. Friendship is not a popularity contest to earn favors; it's about learning who you are as a person and the type of people you want to be with. In order for those people to want to be with you, you have to be able to take care of yourself and show that you care about them. It won't always work out, but it's something to be celebrated when it does.