Many consider that the romance between Nina and Charioce is forced, but I do not think so, and many may disagree with me, but I will say:
Forced romance? Absolutely not, it’s necessary.
Charioce is a central character for the plot of history, without him basically we would not have story, and Nina as protagonist is an external agent of the problem of the three races, she doesn’t belong to any side. Then, with both of them, a romantic story is born that has been well managed since ep. 3, I mean, it was not born of mere whim, but was constructed coherently because it fulfills and will play a role within the development of characters (Nina and Charioce and others) and will also play a necessary role for the plot.
It’s not only because of fanservice (if so it would have been with the most popular character in the series: Azazel, he’s a very lovable character).
It fulfills a function within the story and will advance the action and characters.
The writers not only don’t want to give us an absolutely black villain who only wants power and glory for an unjustified or ill-argued goal, but to show us diffuse and complex characters (Favaro is a great example), but also to show us that in these lines of hate and massacres there can be more than good and bad.
And why would Nina love an evil and cruel king like Charioce? Many claim that he doesn’t deserve it, but if something I know of love is that you don’t need reasons to love someone, you can not give concrete reasons: it’s unspeakable. So don’t look for reasons to love, just love and that is reflected in Charioce, someone aware of all the evil he has done but can love; and Nina is aware that Charioce is not the man you would introduce to your family and friends, but asking not to love is ridiculous. Thinking that there is no reason to be loved is also ridiculous.
So, if you ask me, this romantic relationship between them feels so human, so complex, like all human relationships.
There is no problem with romance if it fulfills a specific role within the plot that for the moment has not been completely defined. This is my opinion.
I would like to know your opinions about it, I appreciate corrections xD