How To Save A Marriage and Ruin Your Life (1968, U.S.A.)

In this fun and breezy comedy about the battle of the sexes carefree bachelor David Sloane (Dean Martin, The Matt Helm spy spoofs & Rio Bravo) tries to convince his best friend Harry (Eli Wallach, The Godfather: Part III) to stop cheating on his wife by suggesting that his mistress is being unfaithful. David seeks out Harry’s mistress to seduce her himself but mistakenly meets Carol (Stella Stevens the Nutty Professor) her next-door neighbor. What follows is a zany string of mistaken identities misunderstandings and comic adventures leading David and Carol in and out of love.