The essence of loss is the realization that something you once had is now gone. It is essentially the awareness that a fragment has gone, is broken off and become irretrievable. The act of loss can be like smoke, visible, twisting, and intangible. Or it can be like a sudden vacuum, the obvious affront of a missing puzzle piece. In either case, the loss is permanent and something irreplaceable has been lost.
Unique. It is easy to see how the idea of a soul comes about. When you know such is lost. It is akin to learning the existence of that aforementioned puzzle obvious through the absence of that piece. Before you thought it was just a landscape in the countryside, now it's a broken toy. That's melodramatic. Stick to the idea that it's a toy, a childish thing. To be left behind by the healthy adult. Grief makes us children, and subject to a child's sense of drama and pain, which are terrible. A fear forms, and a child clings to fear.
I'm full of shit.