I think the song is sort of obsessive (well, duh). The person Amy is singing about was very in love with somebody and he then died. It almost seems to me that maybe he wasn't that much in love with her, maybe not at all. She just got obsessed with him. He might not have even known her or then it was common knowledge that she was very in love with him, even to the point of being dangerous and then he died and she goes to his grave to even maybe physically take his body to keep as her own, she imagines that thus she could make him love her, she could own him.

Sometimes I think that he's been dead for a long time and she actually had his body tucked somewhere (very Psycho) or maybe she even killed him, maybe she only loved the person she made him to be, the tone of the song is so obsessive and excessive in its declarations of love. Eventually it was found out that she has his body and it was taken away from her and buried and maybe the song is about the last night she has, she goes to the grave and kills herself to be with him. Uselessly perhaps, since it seems to me he wasn't that in love with her. The love in this song is in her head to me. She ties herself to him in this almost mystical way. There's no mention of his character or his feelings towards her, compare the lyrics to My Immortal where the person she lost had a face and a presence and features and the singer can recognize bad features in him, can criticize him even if she loves him, she's realistic in her feelings. Even in Death is strictly from her point of view, her imagination.