Lols
Cheerful musics that fits with the cute animations. Good job on that.
However, the game is too unforgiving. One touch from someone bigger and that's the end of your heart. At least include a life system. (3 life for easy, 2 for normal, 1 for hard.) Power ups that occasionally float by would be a really nice addition! There is no sure way of knowing whether you will eat or be eaten by another similar-sized heart, all I could do was to estimate. Maybe you can tint those hearts that are larger than you slightly.
This game was meant to be a mini-game for valentines. Fits perfectly for it's purpose!