I hate to admit it, but I think one thing fueling my emptiness is that I feared rejection and let that fear rule me. Like a comedian alone on stage who is bombing, I treat each interaction I have with life-and-death precision. And, when I don't make the connection with the other person (which is often), the rejection occupies my mind for days. When it finally leaves me, it leaves behind the sadness it was feeding off of so that I feel deficient and hopeless.
One thing I am starting to come to terms with though is, I can survive rejection. Like that comedian I left on stage, it actually can make me less vulnerable (over time) if I use it as an experience to move on from.