There was an ancient Roman holiday known as Lupercalia which was celebrated on February 15th each year. The holiday was to honor Lupercus (the god of shepherds) and Faunus the Roman equivalent to the Greek god Pan. It was also to honor Romulus and Remus, the founders of the city of Rome. Basically it was a fertility festival. I can only imagine.
In 270 AD, Rome was facing a civil uprising. Men were not flocking to Claudius II like he expected them to and decided the reason was because men did not want to leave their fiancees or wives. In response to that belief, he cancelled all engagements and marriage ceremonies. Two priests Valentine and marius (marry us?) refused to honor the new law and continued to perform wedding ceremonies. valentine was caught on Feb 14th and was drug off to prison and was beheaded the same day.
But it is said that during that short time in prison, he met the jailer’s daughter and fell deeply in love. Legend has it that he sent her the a note and signed it “From your Valentine”
Lupercalia continued to be celebrated until 496 AD, when Pope Gelasius changed it to a similar celebration , which he changed to honor St Valentine and he moved the date back one day to the date Valentine died. St Valentine is patron saint of lovers.