Cheesy but what the hell. It's Valentine's Day.
Have a loaf of bread in a shape of a heart. Stick a card (Jack of Heart come to mind) with a corner torn off inside the loaf. Make sure that as little slit as possible is visible. Keep the card's corner.
Get out the deck of cards, and force the dublicate. "Here is something for you, my little Valentine" and offer your heart. (the loaf that is). She takes it, because chicks dig that sort of stuff. Yeah right!
Tear the card into pieces and add the corner from the card that is inside the loaf of bread. Pick up that corner "Here, have that as a receipt of my love."
Then take the remaining pieces (actually the whole card) and vanish them. (Burn them in an envelope or whatever comes to mind)
Now you are ready for the big finale.
"If you wanna know how this trick ends, you have to break my heart. But if you care for me, just kiss me and we forget that there is magic."