The Collaborative International Dictionary of English v.0.48:

Unfellow \Un*fel"low\, v. t. [1st pref. un- + fellow.]
   To prevent from being a fellow or companion; to separate from
   one's fellows; to dissever.
   [1913 Webster]

         Death quite unfellows us.                --Mrs.
                                                  Browning.
   [1913 Webster]