A valentine is a card sent, often anonymously, on St. Valentine's Day (February 14) to a person one loves or is attracted to. Sometimes the valentine would be shaped in the form of a heart.
Mainstream Smurfs Media
In mainstream Smurfs media, valentines are sent by and to Smurfette on both Valentine's Day and Smurfy Friendship Day, with Smurfs hoping to get a kiss from Smurfette in return.
Empath: The Luckiest Smurf stories
In the EMPATH: The Luckiest Smurf story series, valentines were a common thing sent among the Smurfs and Smurfettes of the Smurf Village until the time when Papa Smurf became the sole parent and leader of a hundred little Smurfs. It was when Smurfette became a member of the village that valentines had resumed, with the Smurfs hoping that Smurfette would choose one of them as her one true love.