The earliest possible origin story of Valentine’s Day is the pagan festival Lupercalia which, for centuries, was celebrated in the middle of February. The festival was dedicated to Faunus, the Roman god of agriculture as well as the founders of Rome, Romulus and Remus.
Lupercalia was outlawed, as it was deemed 'un-Christian', at the end of the 5th century by Pope Gelasius. Soon after, the Pope declared February 14 St. Valentine’s Day - a day of feasts to celebrate the martyred Saint Valentine.
It was much later, however, during the Middle Ages, that the day became associated with love and romance. It was commonly believed that February 14 was the beginning of the mating season for European birds. The earliest suggestion that St Valentines Day was a day for lovers is believed to have come from the English poet Geoffrey Chaucer's 14th Century poem, “Parliament of Foules” where he wrote, “For this was sent on Seynt Valentyne’s day / Whan every foul cometh ther to choose his mate".