This is a very historical manwha so it's safe to say that gay relations is uncommon enough that it's not registered as an "ok" or "normal" thing to do. Moreover a big point of the plot is continuing bloodlines which Two believes is necessary and Shu hasn't yet cleared up. Of course, this could be to set up mpreg in the future
Also, its not the "brown savage" stereotype as Shu's kingdom is shown to be very civilized and the reason for all the murder is a curse from their god. Yet another clear plot point that's quite relevant to the plot.
"Historical " or not, the constant reminder just to build tension is fucking annoying. The manhwa insists upon itself and that point. Its played tf out. The author leaving mpreg as an option in the future would make the "but im a male" pount pointless. Thats more agitating.
BWAT has a raceplay theme in all of their manhwas. This trope is imbeded in all their works. The tan character always has a lighter skjn companion that tames them. This manga is no different. The civility or not is not the factor im pointing at.
I just want them to have sex and stop with the angst. Blonde hair is so dramatic and black hair so underwhelming. They keep hitting us with the "im not a women/princess" nonsense and it's getting tiring. The whole blonde family has schizophrenia and im getting over this darkskin trope or "savages that must kill" bs.