Confused about ending

Ya, I think he thought he was protecting Trixie.

no he love his wife and wanted to be accused only for helping her

It's a good question since the movie emphasizes how far a parent will go to protect a child. But it's also about how family protects each other, in this case husband and wife. You can hate the sin but not the sinner. Yes, Daniel hated his wife's infidelity but he didn't hate her. She loved her husband, too. Remember the scene when she tells her lover "I'm using you to remember my husband the way he used to be?" or words to that effect. A movie can't explore the multi layered aspects of the husband/wife relationship the way a novel can. Though their marriage is troubled and problem filled, they are still in love.

I don't think he was protecting his wife. He was protecting Trixie. He knew Trixie didn't do it, but if you listen to his conversation with Trixie in the car before the cops pull him over, he says something like , "I know you didn't do it. But you are guilty if everyone thinks you are." So because everyone would have blamed Trixie, he confessed to the murder so she wouldn't have had to carry that.

Me too. I never read the book, where it might be explained. Makes no sense whatsoever to admit to murder when you think it was a suicide (the father did not know the wife did it, as is phrased by the thread starter). Only the police and the perpetrator knew what actually took place. Or the father would had admitted guilt if he was mentally disturbed, but no indication of this in the movie. This would have been an average movie without this bottomless hole in the plot. Now I say a very weak movie.