Supposedly, Valentine, a priest from Ternia, later canonized as a martyr, was executed on February 14 in 269 AD. The offense of which he was accused: He was said to have performed illegal marriage ceremonies according to the Christian rite. A far more credible explanation is that in the early days of Christianization, it was much easier to win people over to the new faith if they were left with their old pagan celebrations and feast days. Often these were even incorporated into Christian customs.
In the early 4th century in the Roman Empire, Lupercalia, the feast of Juno, wife of the supreme god Jupiter, was celebrated on February 14. Juno was especially revered as the protector of marriage, and on her feast day the giving of flowers is also said to have been common. In addition, couples were said to be drawn to each other as fiancés.
In another variation, a girl was supposed to marry whoever crossed her path first on the morning of February 14 (if that person was unmarried).
Christianity, struggling to establish itself, virtually appropriated pagan customs by attributing them to "Saint St. Valentin" and chose February 14 - the day of his execution - as Valentine's Day.
Even the Kirchenlexikon confirms this variant:
"The custom of giving each other flowers on Valentine's Day goes back a long way: in ancient Rome, the goddess Juno, the protector of marriage and family, was commemorated on February 14. Women were given flowers on this day."
A direct connection of flower-giving to Valentine of Terni, however, could not be uncovered until today.