But it's a perfectly logical ending. A sheltered girl who wants adventure, instead of dominating everyone around her as she intended, ends up in the clutches of maniacs. And she could have continued living as a sheltered girl. It's quite a humbling experience.
Or even better - he lets the fiancé live because Laida can't be killed by anyone, except for a special commando unit from Nihon, and he periodically sends him photos of a happy Livia with various young men in compromising positions.
Where do we end up when we save the world?

