St. Valentine's day is another example of the Catholic Church's need to convert the dirty pagans by usurping and repurposing existing Pagan festivals. Easter, Christmas, and also St. Valentine's day were all actually pagan festivals before they had anything to do with saints, jesus's birth or rebirth.
St. Valentine's day was originally Lupercalia. It was a fertility festival dedicated to Faunus, Roman god of Agriculture and also to Remus and Romulus to commemorate a young man's passage into adulthood.
It was named after the order of priests who began the festival (Luperci, named for Lupercus, God of the wolves).
When the vatican was going *nuts* (well, one of the times) with the need to convert the dirty pagans it decided to rename the holiday after Saint Valentius. A man who was killed apparently for marrying couples in secret against the will of the state when the then emporer was more interested in having lots of single men to be soldiers than in having a happy populace... so he banned marriage.
A lot of bullshit has been written about the St. Valentine holiday and what it means and who Valentine was. Stories differ wildly. However it's only christian sources that claim he was jailed becuase the romans were trying to keep people from worshipping christ. When in fact, in the cast of this one man, they just didn't want him going around fucking up their soldiers by marrying them.
The holiday has NOTHING to do with god or christianity. It has everything to do with a pagan fertility festival (they even got to draw a lotto of all the women in town to see who would be their lover for the next year), and with the willingness of the Catholic church to twist the history of the bible and lie to its own adherents in order to gain converts, and subsequently more power.
(For me... 2/13 into 2/14 is when Karl asked me to marry him. It is also my brother's birthday. Beyond that, it's one of th 10 or so nights a year that we steadfastly avoid any sort of food establishment)