I think that an effective title that would cover the ending to part 2 and the start of part 3 would be "From the Garden to the Desert." This title is applicable in a couple of ways. The first would be that the sections represents a moment in time when Julia and Winston share tender embraces and exchanges about the world and their place in it. If they are ever to be seen as happy, it would be in this moment. When Winston and Julia stare out the window at the singing Prole woman and reflect on their experiences together as well as how they understand the condition of the world in which they live, a garden is evident. This garden is facilitated by their affection towards one another.
This moment is interrupted by the entry of the Thought Police. From here, the desert is evident. In contrast to the affection and sense of wonderment that both display about themselves and the world, there is a crushing paralysis evident in Winston when he sees someone he has affection towards beaten. Neither Winston or Julia can do anything in defense of the other in the presence of the police. The tenderness of the moment in which their love is shared becomes completely undercut by the reality of oppression and control. Winston sitting in the cell and being told to keep his hands in plain sight and not to move is the culmination of the desert, a condition in which the nourishing affirmation of the garden becomes absent. In its place is desolate brutality. In seeking to encapsulate the complete difference between the last moments of the relationship that Julia and Winston share and the result of it being broken into pieces, the title of "From the Garden to the Desert" seems to be appropriate.