An Unmarried Woman is a 1978 film about by Paul Mazursky, which was apparently very groundbreaking at the time, but doesn't seem to have aged to well. The story follows an Upper East Side woman whose husband leaves her and she has to deal with being alone. All in all the story is pretty cliche, she gets upset throws away all the stuff he left behind, goes to therapy, has some casual sex. But similarly to Mazursky's Bob & Carol & Ted & Alice, it is pretty fun to watch, if only for the scenes of vintage New York City artist lofts and Jill Clayburgh dancing around in her underwear.
This guy is a way more successful artist who falls totally in love with her and wants her to marry him and be with her forever, in a slightly too good to be true Something's Gotta Give type scenario.
He gives her that painting. The screen capture is too small but the shoes she is wearing are identical to the espadrilles I just got on ebay. I'm gonna be rocking the 1978 jilted woman art hanging in Soho look this summer.
Then I just happened to read the New York Magazine profile on Sarah Jessica Parker and she mentions An unmarried woman as being a sort of proto Sex in the City.