I have two theories about this song. However, the cheating and two loves theory aren't them. My first and most obvious theory is that he is simply saying he wants to fall in love and give her all his heart, but feels all he has to offer is the leftovers of a past relationship. He can't truly give her all of him because he feels as if his past lover has a part of him and always will. My second theory is that his "other love" is drugs. I may be way off, but if you listen to the lyrics it makes sense. When drugs are your first love, it is hard to give your lover the attention and love that they need because you are consumed. Those were my theories before I watched the video. Now I'm a little confused, but the one about how it's a relationship built on lies goes with the video.