One theory is a Catholic priest, Valentine, was imprisoned for helping Christians escape Roman prisons. While he was imprisoned, Valentine fell in love with a young girl who visited him. Allegedly, before his death, Valentine wrote a letter and signed it, “From your Valentine.” Thus, the first Valentine’s Day card was created, or so it is reported.
However, like many contemporary holidays, Valentine’s Day probably has pagan roots. The pagan celebration of Lupercalia, celebrated at the ides of February, was a fertility festival dedicated to Faunus- the Roman god of agriculture. So it can be derived that from the pagan fertility festival, this was later watered down by the Church and turned into a festival of love. By the 1800s it had become common for friends and lovers to exchange gifts as tokens of affection. Shortly after that, the holiday became commercialized.