The husband is not happy, the wife who secretly incest with her son also has the same content as Secretly watching the father fuck the mother, the son is miserable because... These two films share the same studio and the same series.
Going back to the movie, the title of this film is not exactly accurate and complete, it must be: The husband is not happy, the wife is clumsy with her husband's son; because the heroine in the film is a stepmother, not a biological mother. In general, it's a little wrong, but I think everyone can accept it, the important thing is a good movie, beautiful actors.
As for the content, I have said above, generalizing it is similar to secretly watching my father fuck my mother... If you want to learn about the content briefly, you can click the link above to watch. Greetings.