The origin is this statement:
Statement 1: In the 3rd century A.D., Emperor Claudius II of the Roman Empire renounced all marriage promises in the capital Rome. It was for the sake of war, so that more carefree men could go to war. A priest named Saint Ketus Valentinus did not follow this will and continued to hold church weddings for young people who loved each other. After this incident was reported, Father Valentine was first flogged, then stoned to death, and finally hanged on February 14, AD 270. 14 century later, people began to commemorate this day. Now the Chinese translation of "Valentine's Day" is called Valentine's Day in western countries, to commemorate the priest who died for his lover.
Statement 2: It is said that Valentine was one of the earliest Christians. Being a Christian at that time meant danger and death. In order to cover other martyrs, Valentine was taken to prison. There, he cured the blind eye of the warden's daughter. When the tyrant heard a miracle, he was so scared that he beheaded Valentine. According to legend, on the morning of the execution, Valentine wrote an affectionate farewell letter to the warden's daughter, signed: from your Valentine. On the same day, the blind girl planted an apricot tree full of red flowers in front of his grave to show her mind. This day is 14 February. Since then, Christianity has designated February 14 as Valentine's Day.
Statement 3: In ancient Rome, February 14 was a festival to show respect for Jonah. Jonah was the queen of the Roman gods, and the Romans regarded her as the goddess of women and marriage. The following February 15 was called "Lupsala Festival" to show respect for other gods under Jonah. In ancient Rome, the lives of young people and girls were strictly separated. However, on Lupsala Festival, boys can choose the name of a girl they love and carve it on a vase. In this way, during the festival, young people can dance with the girl of their choice to celebrate the festival. If the selected girls are interested in boys, they can always pair up and eventually they will fall in love and get married in church. For this reason, future generations designated February 14 every year as Valentine's Day.
Statement 4: It originated from the festival of faun in ancient Rome.
According to this statement, the Christian church celebrated this day in order to christianize the faun festival in ancient Rome (celebrated on February 15 every year to protect the productivity of people, fields and livestock). Among the gods worshipped by the Romans, Lubbocus was in charge of the protection of shepherds and sheep. Every year in mid-February, the Romans hold a grand ceremony to celebrate the festival of faun. Compared with now, the calendar at that time was a little later, so the festival of faun was actually a celebration of the coming spring. Some people also say that this festival is to celebrate and bless Nuss, similar to the sheep's feet in ancient Greece and the horned pan in charge of animal husbandry and agriculture. With the expansion of Roman power in Europe, the custom of faun festival was brought to France and Britain. One of people's favorite holiday activities is similar to lottery. The young women's names are put in the box, and then the young men come forward to smoke. A pair of drawn men and women become lovers for one year or more.
The rise of Christianity makes people's custom of commemorating gods gradually indifferent. The priests didn't want people to give up the joy of this festival, so they changed the festival of faun to Valentine's Day and moved it to February 14. In this way, the legend about the Valentine brothers and the ancient festivals are naturally combined. This festival was the most popular in medieval England. After the names of unmarried men and women are drawn, they will exchange gifts with each other, and women will become lovers of men within this year. A woman's name will be embroidered on a man's sleeve, so it is his sacred duty to take care of and protect women.