According to tradition, Valentine's Day is the author of numerous miracles but above all he earns the nickname of patron saint of lovers or "saint of love" when he celebrates the marriage between the Roman legionary Sabino and the young Christian Serapia.

Valentine dies on February 14, 273 AD. by order of the Roman prefect Placido Furio, during the persecutions ordered by the emperor Aurelius. But the international notoriety of Valentine's Day is due to the legend, born in Anglo-Saxon countries, according to which he used to give his young visitors a flower from his garden. A love was born between two of these young people which led to such a happy union that many other couples followed their example, to the point of inducing the Saint to dedicate one day of the year to a general nuptial blessing.

In any case, still today the Festa della Promessa is celebrated every year, in which young boys about to get married and close-knit couples with years of marriage behind them from all over Italy take part. The engaged couple arrive in Terni to exchange a vow of love in the Basilica of San Valentino, where the remains of the saint are kept, to cement the promise of the imminent marriage. Married couples who have reached their 25th or 50th year of marriage also participate by celebrating the milestone and renewing the commitment of their bond.