In response to:
Is it the fear of pain, or the fear of what they will miss? Or just the fear of the unknown?
You don't cry because you fear death, i am not scared of my demise. But, i will cry for the ones that i love that i am going to leave behind. The times of laughter, love, and happiness is what you will see, you will forget the pain, hurt, wrongdoings, etc.
Tears will never be in my eyes for pain, or fear of dying, my tears will be for love.