Having learned that there would be a murder in the movie from the movie description, I found myself making things up. I couldn't get around how a father manages to coax his son to assist in the crime. That is until the scene where Wilfred has a change of heart toward Arlette's request for divorce. It seemed the threaten to gain custody of Henry, the son, was the final deciding factor for Wilfred.
After some contemplation, the father schemes with his son, and as a result Wilfred dumbfounds his wife with a shocking revelation that he apologized for his ways. Arlette is so happy to hear that Wilfred would do anything to avoid divorce, she decided to celebrate and this is the point where Wilfred and Henry get her drunk.
It's during a drunken dancing scene that the idea of incest comes to mind. For one thing, it's the only believable way a straight-laced teenager could ever agree to the crime. The footage of Henry and Arlette dancing is cropped at the waist, so if Arlette had hoisted up her skirt at the point when Henry meets her on the dance floor, I found myself thinking it was totally feasible that Henry already had gotten his boner out of his pants, because what follows in the drunken dance steps Arlette makes, and the inexperience of Henry’s dance moves is totally something I would love to see how was depicted in the script.