I want this, but I don't want this to be a sappy romance. It can start that way, but I want the guy to gradually become more and more obsessed, until he actually starts killing off her boyfriends. Or make it a sappy romance.
The universe is a wondrous place. The first point is catchy, but not strictly correct. Complex atoms that constitute part of your substance had to be created in late-stage stellar collapse, sometimes in stars several generations old.