I Caught My Wife Cheating

Frank is happily married to Shelly (or so it seems). He does all he can to make her happy, including satisfying her in bed. One morning after a marathon sex-session (and before he goes to work) Frank overhears his wife talking to her lover on the phone. His wife plans to have sex with her lover in their marital bed while he is at work.
Frank vows to catch them in the act by getting home earlier than usual. He does catch his wife and her lover in the act but all is not as it seems. It all ends in an interesting twist.