They’re trying not to outlive each other, because he’s promised he’ll be with her for forever, even after she’s gone. So it would have been better if he’d been the who’d gotten sick, but he was so in love it didn’t matter until it actually happened.
So underneath the lid of the grave, he wonders if she would have done the same for him if their positions were reversed. He wonders if, like him, she’d be willing to bury all her feelings with his body, and whether they’d overflow anyway. He wonders if second chances existed for times like these, and if it was too late to get one now.
There’s more than enough time for himself beneath the grave, but somehow, he finds he can’t put everything to rest, not even if there were a way to go back to the beginning.