We go through our lives getting all tangled up. When someone dies the cord is cut. Gazing down, your hold the severed line in your hand and wonder about the cut. Even with the courage to go back to the opera in Vienna or that little bar with no name, it is no longer the same. Without that lifeline, everything is a vertigo inducing free floating monument to the past.
With death, the fear is not of the unknown, not really. It is the knowledge that inevitably we all end up like broken marionettes, slumped over, every string cut.