F or the most part, the trailer for the upcoming film One Night Only looks like the sweetest possible version of a romcom. A handsome, sensitive-looking man (played by Callum Turner) flirts relentlessly with a big-eyed oddball in a sexy dress (played by Monica Barbaro). They bump into each other, nudge each other, roll their eyes at each other. As a YouTube comment underneath the trailer (that has been liked more than 3,000 times) says: “Romantic comedies are back.” However, tucked away in this adorable little trailer is a premise that might just be the most confusing in living memory. As Turner’s character walks lovelorn through the streets of New York City, his voiceover says: “Finding love is hard enough. Try doing it on the one night of the year single people are legally allowed to have sex.” The trailer then hurries along to another procession of meet-cutes and prolonged eye contact.…