Quite a few folks have a predilection for holiday mysteries.
From Mystery Fanfare: Valentine Mysteries
Cozy Mystery, keeps a list of Valentine's Day Mysteries
"I have five different lists of holiday cozy mystery books that I have compiled over the years..... Easter, Halloween, Thanksgiving, Christmas (which includes some Hanukkah books), and Valentine's Day. I have read many of these holiday cozy mystery books, and keep finding more holiday mysteries to add to my lists."
I'd love to post a short Valentine Mystery.