There was. There had to be. They never even tried Armin's suggestion. They never had to sacrifice Historia for it; any loyal soldier would have done in order to buy themselves a decade more at a time. Of course, who knows what might have happened then. Things had the tendency to find ways to go to shit anyway. Maybe they'll never know indeed, but Levi isn't going to excuse Eren's destruction with something like there was no other way.

But it happened, and none of them can change it. Going forward with what they have really is the only thing left to do at that point, and they can only hope to manage to do so with greater care and understanding across the world.

He gives Eren a look -- not necessarily stern, though perhaps there's a hint of what the fuck did I just say in there.

"I never said otherwise."

One doesn't have to change to grow and still end up... not different, perhaps, but not exactly the same either. A higher vantage point, a better view, a deeper understanding; whether or not it all leads to the same place, the path there may vary just a little.

"I believe you." He believes that Eren knows, that he's actually internalized that knowledge, with all the consequences and implications of it. He doesn't quite believe in him, but it's a trust placed in him nonetheless.