And we knew we shouldn't be trying. "and i even wonder if we should be getting under these sheets, we could lie in this bed, but it's empty" in a literal sense, why should you to keep getting into bed with him, when you know nothing is there. In a more figurative sense, why should you try to make something right when nothing is there. You can continue to try and you can settle, but you'll never be happy, the spark is gone.