We are raised to believe (on the surface, at least) that us humans only have so much love to give, and that it comes in a standard round unit: one. After all, we associate love with the heart, and, well, you've either got a whole heart, or you're dead, period. You can't, common wisdom goes, just run around dividing that one heart up freely; to claim to do so means that you're either a fool, or you're dividing up something that is dead.