This is a very simple idea, and a really good metaphor for the embarrassment involved in young love. Although this spot will need some effects to make it work, it’s important that the effects don’t overshadow the character of the girl and boy. It’s not an effects-spot, it’s a spot about love. 

The basic principle for this spot should be that as the story proceeds, the pace increases, the scale increases and the girl more and more obsessively preoccupied with obscuring the hearts and less and less aware of everyone noticing her odd behaviour.

By the last scene, the action should escalate to something quite big, before coming back to a small, intimate moment at the very end.