When Celine Song wrote the script for her debut feature film, “Past Lives,” she was inspired by a conversation she had at a New York bar with her husband and her childhood sweetheart, who was visiting

This is the brief and unexpected opening of Celine Song’s Materialists, a prologue that announces a certain loftiness in the film’s premise. Or in spite of it, as a sudden cut flings us into the classic opener of many a millennial rom-com: the cosmopolitan heroine at her vanity,