A friend is someone you can rely on, someone you trust and love so dearly. A friend can be your human handkerchief and even a punching bag at the same time. A friend will listen to your endless dramas, will always give you good advices and will never get tired to pick you up. Of course, you should be able to do the same things in return if you're a good friend as well.
It doesn't matter how long you've known each other as long as there's respect and trust in your friendship. When you have a trusted friend, there's always someone who will keep you reminded of realities of life. Sometimes we tend to succumb to illusions and make harsh and irrational decisions out of it. But when you have a friend who can be brutally honest with you, then you can be assured that he will keep you on the right track.
If you happen to have a good and trusted friend, make sure to keep him. It doesn't matter if you're both busy with your adult life as long as you always try to communicate with each other. If you have a friend you can lean on and always includes you in his prayers, then consider yourself lucky.
We may lost some, I think it gives us a lesson to learn from it and choose carefully who we are with. That will also give you a chance to re-think what are the things that you need to work on. I'm part of, thankful that I lost some - to have some. Thanks for being part of my journey!