The song seems to be about a lover who died:
“I see a line of cars and they’re all painted black” – The hearse and limos.
“With flowers and my love both never to come back” – The flowers from the funeral and her in the hearse. He talks about his heart being black because of his loss.
“I could not foresee this thing happening to you” – It was an unexpected and sudden death.
“If I look hard enough into the setting sun, my love will laugh with me before the morning comes” – This refers to her in Heaven.