"I wish it had been as simple as just telling you what I knew. Truly, I do, but the visions showed me no useful information aside from, perhaps, the fact that he was gone long enough to grow a beard. Besides that, I was given no specific timeframe, no indication of where or when he would be back. What it showed me was the The Kings of Old running him through with their blades; what it showed me was Noct burned to ash by the power gathered over the generations; what it showed me..." Ignis' words come to a shuddering stop and he turns away, hands curling into fists at his sides as he desperately tries to push back the pain speaking of the visions brings him. "What it showed me was his father pinning him to the throne with his own sword like one might pin a butterfly to a board. What good would telling you this do? Who would it help? Tell me, would knowing this have done anything but crush what hope you had left in your heart?"

Ignis can't say that he's surprised that Prompto had so much to do with Gladio finally having to put distance between them. While Ignis and Gladio's personalities are opposite in ways that usually complement each other, Gladio and Prompto's personalities are opposite in a way that often causes them to clash. With no Noctis there to be a buffer and Ignis himself likely focused on relearning how to do everything in the dark, those clashes would have only gotten worse. This is why Ignis can't find it in his heart to scold Gladio for his actions. They make sense, especially in such a high stress environment.

"It's never too late." This, though, he can scold on, if only lightly. "Not so long as even one person can be helped. You should know this."