My very first friend in my adopted birth country is relocating today with her family to Bangkok. Similar to college, it is natural to befriend coworkers, especially those who are going through similar experiences. She not only took me under her wing and introduced me to various people but also incorporated me into her family. The connection, though, was not superficial as just coworker friends. She was in a different function but since I sat in the same area due to lack of space, her team started calling us sisters.
We have different lives and rarely hung out with each other outside of work once I started expanding my social network and since she had a son to go home to. Many of the friends whom she introduced me to have come and gone since then as I start weeding out those that are truly friends vs. acquaintances. But she has been consistent - a consistent friend who may not agree with everything I do but she tries to understand me, not judge me and give advice based on my best interest.
A few months ago, another expat had told me that she stopped making friends as the expat community is a revolving door, and it was difficult to always see people come in and out of one's life. Now that I have been here for awhile, I will have to respectfully disagree - perhaps her friendships were very superficial (and as it turns out, she was one of those I weeded out because of all the drama, jealousy and passive aggressive behavior).
So while I will miss having her constantly around, I also know that friends are always friends despite the distance. She has made the right decision for her and her family to start a new chapter in their lives.
Update: With our various business and personal trips, we have been able to see each other at least monthly, and have used skype, facetime, whatsapp, and viber to keep in touch daily. Her ex-secretary saw me recently and remarked that I look like I've gained some weight because my 'sister' has left. Upon further clarification, it was because my 'sister' was not here to eat part of my food. I found that comical - sometimes the logic here kills me.