February 14th is called St. Valentine's Day in the West, which is what we often call Valentine's Day. The origin of Valentine's Day is related to St. Valentine.
A long time ago, Christianity was listed as a cult, and Christians were hunted down everywhere. During one of the hunts, Valentine was arrested and imprisoned to protect his followers, but Christians who believed in God miraculously cured the blind eyes of the warden's daughter in prison. The emperor was extremely shocked by this and ordered the execution of Valentine out of fear. Just before Valentine was executed, he wrote a long letter to his beloved. The long letter was full of love and touching. Every sentence was full of love and reluctance for his lover, and signed at the end of the letter your Valentine.
Just after Valentine was executed, his lover, the warden's daughter who was cured, planted a red apricot tree full of her favorite flowers in front of his grave to commemorate her lover. Later, in order to commemorate Valentine, Christianity named the next day St. Valentine's Day, also known as Valentine's Day, to commemorate their love. This is the most mainstream origin of Valentine's Day.
Of course, in addition to this origin, there are many other origins in the outside world, but none of them are as credible as this one.