Why does it take Navier so long to realize that someone is in love with her? Because she was raised from birth to be an empress in an arranged marriage. She had no reason for love.
If you really think about it, Sovieshu's plan was doomed from the beginning as Navier firmly believed that he was in love with Rashta and likely would have never remarried him. He stated early on that Navier would never do anything that would damage her pride, and yet it didn't occur to him that remarrying him back as if nothing happened would be grotesquely humiliating to her. Navier also states she would never want to raise his child from someone else, something that he also failed to account for with his plan.
Rashta always complains that Navier never gave her any help or advice but that isn’t true. Putting aside the notes she left as she prepared to leave for Western Kingdom, Navier gave Rashta the single most useful bit of advice that Rashta never failed to use badly: talk to your man, not me, because you’re HIS responsibility. Sovieshu despite his issues could have nipped the Roteschu problem in the bud if Rashta had communicated the issue to him far earlier before she was forced to take loans from Duke Ergy.
Rashta is a female misogynist who thrives off of male attention. She is almost universally disliked by the women of her acquaintance and those that don’t immediately dislike her all do eventually. Everyone responsible for her final fate is male, while most of her female acquaintances all at one point tried to, if begrudgingly, help her, even Navier.
Heinrey was asked by his brother, the former King Walton III, to take care of his wife, Krista, after his death. That's partly why she got to stay in the royal palace instead of leaving for the royal villa in Compshire like other Queen Dowagers before her, which allowed her to build up power and political connections in the capital. But after trying to become Heinrey's mistress after poisoning him with a love potion (both because of her family and her own romantic feelings towards him), Heinrey orders her to leave for Compshire at once. He then sends a knight to Krista's new home to seal all the doors and windows, only allowing food to enter through a hole in the outer stone walls. He was, after all, taking care of her like his brother had asked him.
Before she left the Eastern Empire, Navier hid a check for 20 million kruts for Rashta to find, along with a budget application for the charities and organizations Navier had contributed to. She also advised Rashta against donating that money in her name, since it could cause issues for her down the line. Rashta ignores Navier's warnings out of spite. Later on, when Rashta threatens to harm Navier's family, Navier asks one of her business associates to pretend to scrutinize an Eastern check, under the pretense of checking for fakes. The businessman whose check was scruntized then looks through all of the checks cashed out within the last year, and discovers that the check Rashta donated was originally under Navier's name, meaning she misappropriated the check. He then reported his discovery to the press, the social and political fallout being so great that Rashta goes into labor early. In other words, Navier attempting to help Rashta be a good empress was also a tool that proved her incompetence.
Fridge Horror
Everything that happened during the series was mostly planned out by Heinrey. He was responsible for mana disappearing from the Eastern Empire and he'd had eyes on Navier for a while. So when Rashta became Sovieshu's concubine, Heinrey, with Ergy's help, used her to further weaken the Eastern Empire's reputation while also getting the opportunity to court the sidelined Navier. If Heinrey hadn't completely fallen head over heels for Navier, and if Sovieshu had not tanked his empire's reputation by allowing Rashta to be his empress, the Eastern Empire would have been invaded by the West, and they may not have been fully prepared for it.
Even if Sovieshu's plan had worked out as he planned, it is heavily implied it would have not worked out in the long run regardless. His heir being the daughter of a woman of low-birth aside, his personal problems made him alienate his allies and make poor political decisions (ruining trade relations with Luipt, imprisoning the new Western monarch, and alienating his former duke family in-laws) that weakened his empire. Rashta's own actions also alienating nobility (such as slandering Nianne and her very close relationship with the foreign Duke Ergy) would mean they would likely not be supportive of her daughter being their next ruler. Furthermore, Sovieshu would also have to hide Rashta's ex-slave status, which if it was public knowledge could spark public outrage and future civil strife that could weaken the Eastern Empire in the long term. Furthermore, his ambitious uncle could easily take advantage of the chaos he allowed by making Glorym his heir to take power. This may have been another reason Navier would never have accepted his plan in the first place, aside from Sovieshu not considering how said child would be raised.
