This song is about Sting's cheating on his wife Francis and the aftermath as he's seeking forgiveness and reconciliation. They had a great marriage (this is metaphorically the "sun") but it was marred by him cheating one time with his wife's best friend (this is the "little black spot" one day). Now that it's out and they've separated, he's seeking forgiveness for the pain that he's caused her. This is why he feels like he's the "King Of Pain". But the only one who can take that away is his wife - if she forgives him - hence "ending his reign". Several other songs reference the feelings and sequelae of his initial cheating and separation/divorce - notably Every Breath You Take, If You Love Somebody, Set Them Free, and Fortress Around Your Heart.
This song is about Sting's cheating on his wife Francis and the aftermath as he's seeking forgiveness and reconciliation. They had a great marriage (this is metaphorically the "sun") but it was marred by him cheating one time with his wife's best friend (this is the "little black spot" one day). Now that it's out and they've separated, he's seeking forgiveness for the pain that he's caused her. This is why he feels like he's the "King Of Pain". But the only one who can take that away is his wife - if she forgives him - hence "ending his reign". Several other songs reference the feelings and sequelae of his initial cheating and separation/divorce - notably Every Breath You Take, If You Love Somebody, Set Them Free, and Fortress Around Your Heart.