What's the Prisma OP joke?
Yeah. Pandora seems to have lapsed into infacy a number of times since Darius's "death." From time to time, she'd also ask Darius if he'd heard the voice of the Fairies again, like she was trying to remind him of his past/origin. Unfortunately, he was too far removed from it all to feel any weight in those words.
Before our journey through time started, Pandora was just finding her footing again, so having her take the next step forward (and likely get back to that kind of active mindset towards Darius) is almost guaranteed to be what's needed to break the stalemate and get a satisfying ending for both characters.
On another note, the way Pandora parallels Miyu adds a lot to their dynamic. Like Miyu, Pandora ran away into despair and was only able to find the light after leaving her shelter and facing all she ran from. A lot of weight came from having Miyu be the one to give Pandora that push, and there's a good bit of irony that Miyu was being made to suffer to end Pandora's suffering when they're so similar in origin.
And while this may not have been Darius's exact intent for Miyu, in OUTS, Kiritsugu mentions a method of salvation that would immortalize Miyu within the planet to save the world, which would have put her in the exact situation Pandora was in. Very cool tie-in now that we know more about Pandora. Really looking forward to what's to come.