I found the movie A Good Marriage on Netflix. It stars Joan Allen and Anthony LaPaglia. It's based on the story A Good Marriage from Full Dark, No Stars by Stephen King. It's not exactly the same as the book version, but it has all the same horrible believability as the written work. I thought the book version was better, but the movie is worth watching.
I give it 4.5 stars. If they'd stuck closer to the original story, I think they'd have been better off.