In 3-quart saucepan, cook marshmallows and butter over medium heat, stirring constantly, just until marshmallows are melted. Remove from heat. Stir in food color.
Stir in popped popcorn until evenly coated. Cool 5 minutes.
With buttered hands, shape 1 cup mixture into heart shape. Repeat with remaining mixture. Wrap each heart in plastic wrap.