Diary of a Mad Old Man (1987)

Marcel Hamelinck has a chronic muscle disease and therefore has to retire from his work. After his wife Denise dies, his attention is drawn to his daughter-in-law Simone. Obsessively he tries to make overtures, even at the expense of his own health. He gives her expensive presents and builds a pool to see her swim. After Simone allows him to touch her, Hamelinck only has one wish: to become her slave. Simone cleverly exploits the situation, while Marcel's condition slowly worsens.