This explains it but the bold parts are part of the problem of self-hating Jews but it's expected since this article is from Am Ha'Aretz.
A Jewish reason to hate Valentine's Day
There are many historical reasons for Jews to avoid February 14, apart from its blatantly Christian name and immodest connotatins.
By Uzi Silber | Feb.14, 2008 | 12:00 AM | 2
Beginning in kindergarten, our Upper West Side yeshiva teachers and rebbis implanted within us a virus known as Halloween Aversion Syndrome. This virus programmed our minds to utterly reject the dastardly thirty-first day of October and its wicked tradition of trick-or-treating. Halloween was muktzeh, idol worship, and pagan witchcraft rolled into one.
Our instructors would remind us that this was a particularly popular day for desecrating Jewish cemeteries.
In my case, their work bore fruit: I never trick-or-treated in our building on West End Avenue, nor would I distribute candy to all those pagan children in costume who came knocking at our door.
A similar process occurred with respect to St Valentine's Day, with its blatantly Christian name and immodest connotations. As a result, I instinctively recoil from all things Valentinian.
My anti-Valentine infection puzzles and disappoints my wife. She was raised in a particularly un-Jewish suburb in New Jersey, where, like everywhere outside the yeshiva world, Valentine's is diligently observed with red hearts, pink greeting cards, romantic dinners and bribe-like gifts of roses, jewelry and lingerie.
To her misfortune Valentine's antipathy was deeply embedded within me, and despite her best efforts, I remain thoroughly ambivalent about St Valentine's Day. A dozen roses are all it would take to please my wife, yet the virus causes me to routinely 'forget' to pick up a bouquet.
The virus was also responsible for my failure many years ago to secure reservations at a certain French restaurant on Lexington Avenue that my wife had eyed for some time. While initially upset, she was understanding upon discovering that the restaurant's menu consisted exclusively of braised rabbits, sautéed frogs, fried snails and boiled shrimps ? not very enticing for this kosher husband.
So whence this festival? St Valentine was a martyr of the late Roman Empire; actually there seem to have been three or even four Saint Valentines, all supposedly martyred in late antiquity. A feast on this day was established in his, or their honor. However many St Valentines had really existed, all would be no doubt disturbed by the contemporary nature of the day that bears their name.
The amorous legends that came to surround this day are understood to have been developed in 14th century England, notably by Geoffrey Chaucer and his circle, when the feast day of February 14th first became associated with romance and erotic pairing, at a time when courtly love was emerging into vogue. It didn't become a full-fledged commercially viable love-day until the 19th century.
Actually, Valentines might have been a Christianized version of Lupercalia, an ancient post-winter-early-spring Roman fertility and purification festival that was observed on February 15th in which boys slapped women with bloody goat's hides.
The amorously-charged Carnivale celebrations and its American variant known as Mardi Gras also take place at this time. And Purim, which also may have originated as a Persian winter's-end festival, falls around now on non-leap years.
Not to be a romantic spoiler, there is a grim, long forgotten reason for Jews not to rush out to invest in lingerie or make dinner reservations. According to Cecil Roth in his classic 'The Jewish Book of Days', it was on this day in 1349 that the Massacre of Strasbourg took place, perhaps the worst of the many anti-Jewish outrages that occurred during the Black Death. The locals had blamed fluctuations in the price of corn on the Jews, whom they suspected of being protected by the city council.
It was on February 14th that a mob barricaded the Judengasse (Street of the Jews) and drove the whole Jewish community into the cemetery where they built a huge pyre. About two thousand Jewish men, women and children were burned to death.
A new council was installed shortly after, and officially barred Jews from the city for a century. As it happens, this ban was eased 20 years later.
Among the spoils of that day was a shofar the mob had found in the main synagogue. This find confirmed the suspicions of the townsfolk: it was, they said, prepared by the Jews in order to betray the city. By blowing it, the Jews would be able to signal their unnamed allies lurking outside the city walls.
For many years after, the so-called 'Judenblos' was blown each evening on a 'grusselhorn', an imitation shofar, as a warning to any Jews within the city limits to depart before nightfall, and also as a reminder to the townspeople of their 'miraculous' rescue from the machinations of the devious Jews.
Jews could be forgiven then for choosing to skip Valentines. That's not to suggest however that romance is lacking in the lives of Hebrews: six months from now is the 15th day of the month of Av. Commonly known as Too b'Av, this is the Jewish love-fest. It's just as ancient as the Roman Lupercalia and at least as erotic as the Catholic Valentines.