Death is always painful when it comes because it means that a person is cut off from the world of the living. It means that between the dead and the living there comes a distance much farther than the farthest point on this earth. When a person lives, once can always hope he will come back home sooner or later, but when a person is dead, one can only hope to join him someday.
There is nothing final in death, which no one ever likes. When death comes, it's all over for the person this side of life. No matter how miserable one's life my have been, death appears always terrifying. Life is just too beautiful to end in death. But faith teaches us that death is the necessary passage to eternal life. Jesus said, "Unless the grain of wheat falls to the earth and dies, it remains just a grain of wheat. But if it dies, it produces much fruit." (John 12:24)