I gotta say that this story has been strongly political since the start. It's definitely more serious than something like Survive as the Hero's Wife, Empress of Another World or anything like that. This is not a doki doki story. This one focuses on forming an empire and the instability that comes from it. True, monogamy became the norm later in Western civilizations but this story is not set in such a culture. Besides, the emperor at this point has given up on being with Paul. This story is slow paced and goes through many years. If Paul does end up being empress it won't be if not after several more years and circumstances that lead her to the throne. The emperor values Paul too much to just make her a side concubine or a mistress.
Also, I read some spoilers (you may continue reading if you want) and seems like the concubines will all either die or divorce.
DROPPED. I HATE HAREM.