Okay - I got this from Dear Abby's column the other day.
According to npr.org, the celebration of Valentine's Day started in ancient Rome and contains elements of both Christian and pre-Christian religions. In the third century A.D., two men named Valentine were executed by the emperor Claudius II in different years on Feb. 14, and a few hundred years later, a pope (Gelasius I) combined St. Valentine's Day with Lupercalia -- a fertility feast -- to replace the pagan ritual. (Research this online if you wish, because I found it fascinating.) The holiday didn't become romanticized until the Renaissance.
I have no idea if it is accurate.