There are at least three theories of St. Valentine's Day and each of them is far from clear and too lengthy to explore here.
Whatever version you be wish to believe, they do all have at least one thing in common: At some point in the early days of the Catholic Church (around 250 A.D.) there was a priest named Valentine or Valentino.
It was said that he did good things for various groups of people which for some reason the Romans found objectionable.
Written Valentines however did not make their appearance until the 1400s. That's when it took root as a tradition to be celebrated every February 14th.
So there goes the theory that it was invented by Hallmark Greeting Cards or chocolate companies or rose growers.
Whatever! Happy Valentine's Day