As with all other holidays, the Valentine's Day sales push starts earlier every year. I saw hearts and cupids in stores on December 26th. There's no point in fighting it. Besides, it just means more opportunities to by special holiday candy.
It happens to me every year. I throw myself wholeheartedly into the build-up to Christmas: the Advent church services, the decorations everywhere, the heavenly holiday foods, even shopping for presents, and, of course, the Christmas music. But on December 26th, I get the dreaded post-Christmas blues.