Breaking down the story...SPOILERS

This is a very deep story of love, falling out of love and into hatred and how petty relationship problems can kill.

Jack is a professor who starts out young and avant-garde but after living long enough with Howard and Judy he becomes embittered and when Judy refuses to leave Howard and move away with him, Jack cheats on her and leaves.

The regime starts to change and the regime harasses them, but then they start killing all their friends. The regime changes again and Howard is murdered.

Judy moves away and meets Joan, and then she's murdered.

I think Jack was an informant and they were killed on purpose.