Sorry to be the one to tell you, but that website is satirical, and Galenalia is made up. However, there are some popular beliefs that Valentines day is a Christianization of the Lupercalia, a genuine Roman festival celebrated between 13-15th February. According to some traditions, in the 490s Pope Gelasius I abolished the Lupercalia, which had been the last remaining pagan festival celebrated in Rome, replacing it with either Valentines Day or Candlemas (when Christians celebrate the presentation of Jesus in the temple and the purification of the Virgin Mary).

This doesn't work for a couple of reasons. The first is that the chronology doesn't match up. For one thing, Candlemas had been celebrated for at least a century by the time of Gelasius, although in Jerusalem rather than Rome, and had always been held on Feb 2nd. The early history of the cult of St Valentine is hard to trace, but there's no real evidence that Gelasius linked it to the Lupercalia. He certainly forbade Christians from celebrating the pagan festival, which seems to have hung on in some form or other into the fifth century, despite repeated banning of pagan worship by various Christian emperors since Constantine. Presumably all religious aspects had been removed, keeping just those parts that were mostly inoffensive to Christian authorities. However, there is no mention of either St Valentine or Candlemas in Gelasius letter condemning the Lupercalia.

The second reason why the Lupercalia is a bad model for Valentines day, at least as a celebration of romantic love and an occasion for courtship, is that this wasn't the purpose of the Roman festival. The Lupercalia was predominantly a purification festival, although it was connected to human and agricultural fertility. As part of the ritual, young men would run a circuit around the centre of Rome, carrying strips of dog or goat skin and using them to playfully whip individuals in the crowd. Women would sometimes intentionally stand in their way, because it was believed that to be hit by these whips would increase their chances of getting pregnant, or perhaps cure infertility. However, and importantly for the supposed connection to Valentines day, there is no sense that these women intended to start relationships with the men who hit them. The increase in fertility was really aimed at flocks of livestock and fields, and only human women by transference. In contrast, Valentines day is not, nor has it ever been, a festival linked to fertility. Moreover, the association of the day with romantic love can be found no earlier than Geoffrey Chaucer in the 14th century.

So there you go. There's no pagan origin to Valentines day. Sorry!