One Sin a Month (1949)

Paloma and Marcelo are in love, but only dare meet once a month- see, she doesn't know that he is only pretending to be the son of rich ranchers, and he doesn't know that she is only pretending to be the daughter of the great business tycoon B. Quintana... she is in reality just an employee! But when a desperate Marcelo must take a job at Quintana's company, both their lies begin to unravel.