The Grass Is Greener (1960)

Victor and Hilary are aristocrats whose fortunes have fallen so far that they open their English mansion to guided tours. During one visit, wealthy American oil tycoon Charles Delacro crosses paths with Hilary and quickly shows interest in more than the house. As Charles charms his way closer to her, Hattie Durant sets her sights on Victor, turning the household into a complicated romantic triangle.