That Funny Feeling(1965)

She "borrows" his Apartment - then steals his Heart!

Joan Howell, a young and pretty maid-for-hire, meets and begins dating wealthy New York City businessman Tom Milford. Embarrassed about bringing him back to her tiny apartment that she shares with her roommate Audrey, Joan brings Tom over to a fancy apartment that she cleans on a daily basis not knowing that it's his place. Tom plays along with the charade despite not knowing who Joan really is, while she tries to tidy up Tom's place not knowing who he really is.