The whole concept of these two fighting to "save" each other is ridiculous, because the two of them - plus Ms. Immortal and their other allies - could personally demolish the entire system of government under which their deeply problematic society operates. They have the power, both magically and politically, to bring the whole thing down without either of them having to sacrifice themselves like this.
This series has indirectly made the case so many times now that the entire monarchical and "noble" system should be completely obliterated, but it refuses to commit to the notion. I'd argue that this is because Japanese media is still far too fixated on ideas of royalty and nobility, which is a huge part of why European fantasy settings from the Middle Ages to the early Enlightenment are so ubiquitous.
For a series with "revolution" in the name, this story is still fixated on defining who's the right person to rule. Left unasked is the obvious question of why the people should be ruled at all.
Hereditary monarchy, landed gentry, even "noblesse oblige," it's all self-serving garbage used to justify profound social stratification. End all caste systems, without exception.