How about a comedy of errors with no romance? Maybe a group of aromantic people trapped in an elevator on Valentine's Day, and the movie ends where everyone is STILL aromantic, just with a different perspective. Or a thriller that takes place on Valentine's Day that has one asexual protagonist... Don't give him/her a love interest, or a witness to protect. Maybe a business partner who dies early on, someone with no romantic attachment.
Wait a minute... I just remembered something. I wrote something resembling a novel YEARS ago in which an aging gangster in Nevada was murdered around Valentine's Day... just not, you know, anything like the actual gangland St. Valentine's Day Massacre. Maybe I should work on turning that into a screenplay.
Hmm. Speaking of screenplays, the movie The St. Valentine's Day Massacre, starring Jason Robards, was actually pretty good, now that I think of it. I think I'll see if I can track that down and watch it. Happy Decapitated Priest Day, everyone!