The Lupercales (in latin "lupus" means wolf) were tied to the roman origins and pull their name of the Lupercal, a cave at the side of Mont Palatin, in which the she-goat sucked the twin Romulus and Remus. Thus saved by the she-goat, they grew and, later delimite and built Rome.
So Lupercales became the biggest festival of recognition and fertility.

This festival was composed of three acts : a goat’s sacrifice, a Lupercales’ running and a banquet. The essential was the Lupercales’running that ran half naked, hitting women with the lashes cut up in the animal’s skin. The knocks of the lashes were a rite of fertility which women were pregnant and waited happy freeing.

The Lupercales subsisted a longtime since the pope Gelase the 1^st didn’t obtain the suppression in 495, it was for him the festival of fiendish religion.
The Lupercales were without a doubt among the last pagans rites to disappear from Rome, from now on christian.

It appeared so plausible that the Church, to erase memory, had incerased Saint Valentin festival which was celebrated the day before.
So Saint Valentin would have become protector of couples. This way to do is constant in the church which christanized festivals and pagans places.