The dialogue spoken in this last episode (in the non-beach scenes) wasn't well written. Also, at the end, if Juliet hid the key because she didn't want Kate leaving her behind and alone, that wasn't explained too well. They almost made it sound like Juliet had handcuffed herself to Kate, and carried her out into the jungle, in an attempt to convince Kate to allow her to live among the non-others. (And I'm supposed to believe that Jack was asleep that whole time?)