This is difficult to maintain for shared group experiences though. For example, I went on a group trip in 2004 to Europe with a group of strangers. I became friends with a few and interacted with many. Sure I could keep in touch via email or phone with the few, but what we really value about those 10 days was the shared group experience. A 20 person conference call seems much less viable than a Facebook group with the occasional reminiscing post. This starts with a friend request.

Of course this escalates quite quickly. Shared experiences as classmates or part of a student organization or even a workplace. We used to only have the option of maintaining individual relationships. Now that we have the option of maintaining group relationships, the definition of "friend" is fuzzy.