Barbara Stanwyck & Fred MacMurray in Double Indemnity (1946, dir. Billy Wilder, based on the novel by James M. Cain)
I knew then what I had done. I had killed a man. I had killed a man to get a woman. I had put myself in her power, so there was one person in the world that could point a finger at me, and I would have to die. I had done all that for her, and I never wanted to see her again as long as I lived.
That’s all it takes, one drop of fear, to curdle love into hate.
- James M. Cain, Double Indemnity