Elijah tells himself, sometimes, that it's a good thing he'll be gone soon because then he won't have to see Petunia get married. Of course, he does plan on living long enough to try and prevent such events from occurring, from dissuading Petunia from all things male (and possibly, most definitely female) and romantic and tempting. Yes, tempting enough that she may -at some point, unbeknownst to him- shed the last ounces of her immaturity and prove herself, all poised and growing, all grown up and ready. Elijah can barely stand the idea of her being interested, let alone actively seeking and waiting for that time and that right man who, in Elijah's opinion, will never be the right man. There is no man who can match her curiosity, her charm and fierceness and all delicate things that come with being a girl her age (she's not a lady, not like the ones he knows). There will never be a perfect man, nor a noble one because Elijah knows of the world and her villainy and knows men only go so far as to withhold themselves from doing the terrible things they do. They're always struggling, always keeping themselves at bay; some men do it better than others, and some don't hold back at all, as he's learned. He doesn't expect Petunia to understand much of it, not when he doesn't understand some of it, and resolves it within himself by simply realizing it doesn't matter. But when that day does come, when Petunia thinks she understands and meets a man and thinks he might be the one, Elijah will either tell her otherwise or hopes to be dead. The latter seems more plausible.
And he knows Meredith won't stop it, because Meredith has always been much more expecting, accepting and knowing. Meredith has always understood the secret dwellings of Petunia that have entirely evaded him, just like when she was springing into her teens and would often yell at him and slam doors and Elijah would look to Meredith for an answer and Meredith simply gave him a knowing look. Yes, Meredith has always been accepting of every aspect of Petunia- but Elijah knows this might be an exception, because he sees the danger there and knows Meredith shares his fears. There will never be a right man. To them, the right man is a fabrication and a falsehood. Anyone who would try and disagree would only see the sharp end of their ambition.
So Elijah hopes Meredith will stop it, or protest, or do anything, absolutely anything except allow Petunia to get married. It's a flimsy hope, precarious and fleeting as the rest of his hopes and wishes that Petunia will remain how she is, unchanged and suspended in her youth. Even after he's gone. Forever.
He wouldn't be able to bear the sight of her in a perfectly suitable white gown, with her hand-me-down jewelry, necklaces and bracelets and her earrings (she tucks her hair behind an ear to display them more proudly). He doesn't imagine the shuddering in his ribcage when he thinks of how she might look, perhaps as terrified as he'd be, but impossibly happy and worried that she might not be doing something right, despite that everything would feel right to her. And he doesn't even try to visualize the lasting moment of her smiling and watery eyes as she hugs him and Meredith and the words that tumble out of appreciation, of joy, that they were here to see all of it. It all makes Elijah sick to his stomach. He wants to be dead.
"Don't leave me." He faintly says, but not quite to anybody in particular because everyone is gone and she's gone. Elijah sees Meredith and the expression on his face reminds him of how one feels when they feel the pain of a limb that is no longer there. A phantom limb that still aches, still bleeds. Elijah doesn't know if he's an attachment of him or if it's another way around, but regardless of that Meredith looks at him and feels it too. And before Meredith can say anything else, Elijah accuses: "Why did I have to go through this?" He suspects later that he actually didn't say it because Meredith only smiles and it's a small, comforting smile. Elijah doesn't fight against it, he never does. He wants to be selfish for the moment when he can fall apart against Meredith and have Meredith put him together again.
But as it turns out there isn't a later, because Elijah knows even beautiful things like dreams and visions are what they are, and the end is as resolute and imminent as anything else that has been done in his life. Death is not welcome, but accepted. He'll accept it. But it doesn't stop him from admitting to himself, because no one else is here, that Petunia would have looked radiant.