Valentine's Day is a romantic comedy that follows the lives of several couples and singles in Los Angeles as they navigate the highs and lows of love on Valentine's Day. The film weaves together multiple storylines, including a florist who realizes she has feelings for her best friend, a high school boy who plans an elaborate promposal for his crush, and a married couple dealing with infidelity. As the day unfolds, these characters' lives intersect in unexpected ways, leading to heartwarming and sometimes heartbreaking moments.