[dude_abides]

Circles need not be just concentric circles like in your example. People have different groups of friends, each of which is a (probably overlapping) circle. Further, the edge weights between users in the two directions need not be reciprocal. And to complicate things further, these circles are transient, not permanent.

And that is exactly why it is such a hard problem to solve. Any naive UI that attempts to solve this problem will putt too much cognitive load on the user.