A few suggestions? Awesome game. :)
The only things I could really suggest are to keep the game going at several different levels--say, you start on easy and go up to hard, and then you have an unlockable level like "SUPERHARD" or something.
Also, you could put a little box at the bottom with a number of the hearts that you've merged together and give a little indicator on how many more hearts you have to get before you get bigger. :)
I really like this game--I used the retarded cow valentine for one of my best friends. XD
It's really sweet that you and your fiancee worked on this together. <3
I loved the game and can't wait to see more games in the future. :)