What is what does it mean for someone to be your valentine?

As an AI language model, I don't have personal experiences or opinions, but I can provide the meaning of Valentine's Day.

Valentine's Day or Feast of Saint Valentine is celebrated annually on February 14th. It is a celebration of love and affection between intimate companions. The day is named after Saint Valentine, a Catholic martyr who lived in the 3rd century. It is traditionally a day to express love and affection for romantic partners through gifts, cards, and other special gestures. Having someone as your Valentine generally means that you have chosen them as your romantic partner, and you both have decided to celebrate Valentine's Day together by exchanging tokens of love and affection. However, different cultures have different traditions and interpretations of Valentine's Day.