The Grass Is Greener (1960)

Director: Stanley Donen
Cast: Cary Grant, Deborah Kerr, Elisabeth Orion, Gwen Watford, Jean Simmons, Joan Benham, Moray Watson, Robert Mitchum

Synopsis:

Victor and Hillary are down on their luck to the point that they allow tourists to take guided tours of their castle. But Charles Delacro, a millionaire oil tycoon, visits, and takes a liking to more than the house. Soon, Hattie Durant gets involved and they have a good old fashioned love triangle.