The central twist of "Divorce Italian Style" lies not in the execution of Ferdinando's plan, but in its ultimate, ironic futility. Throughout the film, the audience is complicit in Fefè's morbid scheme, following his meticulous efforts to push his wife, Rosalia, into an affair with her former flame, Carmelo Patanè. His plan largely succeeds: he successfully records their intimate conversations, orchestrates a public discovery of their elopement, and tracks them down. As planned, he murders Rosalia, and after a trial where his lawyer successfully argues it was a "crime of honor," he is given a short prison sentence of only three years.
Upon his release, Ferdinando is greeted as a local hero and finally marries his beautiful young cousin, Angela. The film appears to be heading towards a darkly triumphant, if immoral, happy ending for its antihero protagonist. The final scenes show the happy couple sailing on a yacht, basking in their newfound freedom and love. This is the resolution Ferdinando has dreamed of and meticulously planned for.
However, the devastating and brilliant final shot completely subverts this conclusion. As Ferdinando and Angela kiss passionately on the deck, the camera pans down to Angela's feet. She is seen sensually and secretly rubbing her foot against the foot of the young, handsome pilot steering the boat. This single, silent action reveals everything. Angela, the supposed angel and symbol of pure love for whom Ferdinando committed murder, is already betraying him. The hidden meaning is clear: Ferdinando has not escaped his marital prison; he has merely exchanged one for another, potentially more painful one. The cycle of infidelity and dissatisfaction is destined to repeat itself. This final twist underscores the film's ultimate cynical message: the true trap is not law or society, but the flawed and fickle nature of human desire. Ferdinando gets exactly what he wished for, only to have it revealed as a hollow victory.