My Wife, a Body to Love (1973)

Beautiful Simona is married to Paolo, a stockbroker. However she betrays him with younger Marco, an old acquaintance of hers. Paolo, always busy with his business, is used to considering life as a game. When he finds out her betrayal, he remains impassive and does nothing to stop the triangle. He also seems willing to accept a "ménage à trois", but one day, suddenly, he rethinks or lets himself be taken by a raptus of jealousy. Things will change quickly during a beach vacation that will bring the three together for the last time.