Sweet November (1968)

Sara Deever, a kooky Brooklyn Heights girl, sublets apartments and paints in her spare time. Each month, Sara selects from her lodgers a new lover - but only on the condition that he will let their affair end when the month expires. When Charlie Blake, a box manufacturer and her lover-of-the-month, falls in love with her, he is unwilling to give her up. Sara insists, even though it is obvious that she too has fallen in love. As the month runs out, Charlie searches desperately for the key to Sara's persistence. What he discovers provides the haunting climax to this love story.