How is it justification? Not asking in a malicious way but they clearly stated this is a work of fiction, not all relationships on any spectrum of sexuality end up lovey dovey and 'normal'.
Aside from that, this is set in a different time period which allows for abuse of power. If anything, it's realistic.
Oh more certainly not. But it's not real life. Fiction is supposed to touch sensitive subjects and show stuff from different kind of view. Why did everyone love killing stalking shipping the relationship? It was sick. But it was a work of fiction. A made up story with such and not other plot. Not everything has to be realistic. That's what fiction is for.
Also, in one Q&A an author replied to a question of if they'll ever just be together and love each other. The author answered 'in their own way'. And that's how I see it. Some relationships are toxic. A lot of people also need to realise that it's fiction. No one preaches those behaviours. Real world is one thing, stories are other. You can't compare it.