I remember getting a chain email back in college when email was still new - these are now the infamous copy and paste status updates. The email dealt with friendships. I no longer have the original, but the gist of it was people will move in and out of your life. You may form bonds with these people, but remember these relationships have purpose. Some will come for a season, some with a specific reason and some for a lifetime.
If you choose to believe, and I do, that people come into your life to serve a purpose - to teach you, or help you through something - then i believe you must also accept when that purpose is fulfilled s/he may leave your life. Some leave graciously, as if on the wind and you don't necessarily notice their absence until a chunk of time has passed. Others leave with a flourish, negative or positive, but a flourish, being sure you will never forget their existence.
I remember reading that email nearly 15 years ago and being distraught because I didn't want to accept that some of my supposed friends would walk out my life. I have since changed my stance. I am thankful for the lessons these people, kind and otherwise, have taught me. I would not be who I am without their involvement. I have also realized that I may be the drifting friend in someone else's life. I hope to fulfill whatever my needed role is with grace and understanding. I hope that I bless those with whom I connect. If not, please know the less than positive interaction was unintentional. I wish for you the best! Please, pass on the blessing to the next teacher who enter your life.
Thank you for coming into my world. Stay as long as you need.