The weak one dies after giving birth to a princess. More over it’s between her living of the baby and she makes the ultimate call to save the baby above all else. This princess later becomes the next empress kinda a wish fulfillment on the mother’s half who was greedy for actual power and prestige not just that of her husbands. Her death and the birth of the princess leads to Our main girl Paul and the emperor having a fight and her getting engaged, and it also breaks the emperors heart
. Not only because he just lost some one he cared about, but also because his one love decided to up and marry a boring if not terrible guy. The blond one gets kicked out (kinda) for treason? I believe? Pretty much her backers are sneaking around and being shady. And I think the other one who had a false pregnancy leaves by choice? I think she either wanted to find actual love or also did some sneaking around... not quite sure which. I don’t remember when this happens, but that’s what I’ve gotten from the MTL and spoilers I’ve read
Basically it means that Paul is the only queen and the only empress he’s ever crowned.