It's a good line. He wants her to stay safe. He needs her to keep living for him. Where do fallen angels even go when they die? He guesses he'll find out soon enough. Maybe he'll just -stop. Stop existing. No eternal place of happiness, no eternal torture. Just... nothing.
"Just... don't come too soon, you hear me? I want you to join me because of old age nothing less. Deal?"
His own tears fall, but it's exhausting. Everything takes so much effort. He fights to stay awake. He knows if he gives into sleep that'll be it. "I love you, Anna. Always remember that."
He's eyes flutter shut. Battling with consciousness is too hard. It's a futile effort. His breathing shallows, his pulse weakens.