@PerseusArchean Sorry, it was late and my explanations devolved as I became more and more tired. It's not that Jera wants to end the world, it's that she wants to overcome the end of the world. In her eyes, anyone can defeat a mortal or a god, but the greatest for would be fate/destiny. She thought Ragnarok was assured and that she'd be able to fight in and stop the Norse end of times.
Until Cythlla killed Fenrir, a key figure in Ragnarok.
Now, with the wisdom of Minerva, she had to reassess her goals. As a result her definition of "End of the World" became closer to "End of an Era." If the original god were defeated by the Merged, that would be the end of
their world and, as mythological history has shown time and again, gods are
always defeated by their children in one way or another, as was shown with the Titans.
As a result, Jera sees the gods as inevitably losing with their "world" ending. She doesn't want to fight the "easy" battle by joining with the Merged, she'd rather the challenge of fighting alongside the doomed Pantheons.