It's got a whole lot more to it than a dozen roses.
The 14th-century English poet Geoffrey Chaucer is seemingly the first to have associated St. Valentine’s Day with erotic desire and romantic love. In his poetic meditation on love as seen throughout creation, he sees that Nature has destined that it be: “on Seynt Valentynes day, / Whan every foul cometh ther to chese his make,” that is, “on Saint Valentine’s day / when every fowl comes there to chose his mate.” From these few lines developed many other traditions and legends about St. Valentine and his secretly marrying young Roman Christians against imperial edict, including notes that he signed “From your Valentine” to those he helped.
The truth is, the oldest historical accounts of the 3rd-century priest we honor on that day (there are lots of St. Valentines by the way, but it seems to be the Roman priest the day commemorates) say nothing about his connection to romantic love but are unanimous about two things: That he gave witness before the Emperor and other officials as to the truth of Christ and the falsity of the Roman gods, and that he healed one of the officials’ adopted daughter from blindness before his execution. (These traditions are preserved in one of the Middle Ages’ best-sellers: The Golden Legend, a compilation of the lives of saints by the Dominican Friar James of Voragine in the mid-13th century, but the material about St. Valentine comes from the much earlier Life of Saints Marius and Martha with whom Valentine was martyred.)
According to the accounts, Valentine was arrested by order of Emperor Claudius (this must be Claudius II, “the Goth,” who ruled from 268-270) and was questioned about what he believed about the Roman gods. Valentine responded: “If you knew the gift of the Lord, you and the whole Republic would rejoice. You would renounce the demons and idols that your hands have made and believe in God the Father, the all-powerful Creator of heaven, earth, the sea, and all the things in it. You would believe in his Son, Jesus Christ.” The Emperor was apparently astonished and compelled by Valentine’s conviction in the face of certain death. The Emperor’s officers convinced him, nonetheless, to keep Valentine in custody.