Movie title Man kills woman?

I saw a film once. At the beginning, a man and a woman are in love and sleep together. The man promises to always love the woman because that is what she wants from him. The woman gradually becomes more and more difficult and unfair to the man. Over time, she turns into a real fury. When the man is quite old, he kills the woman. He has never accepted his wedding ring until then. He washes the blood from his hands and then puts it back on. As far as I remember, he is being interrogated the whole time and the story is told sort of casually. I seem to remember that at the end he hangs himself from a tree in his garden.

Can anyone help me find the title of the movie/crime thriller?

Thank you in advance. ☺️