She was raped by one of her homeland superiors, right in the beginning of her military training. And yes the Emperor was a jerk. In the manhwa, they tone it down, but Lucius pretty much did the same, told his men to rape her because of some superstitious bullshit.
The novel is good itself, it's really hard to read and not feel bad but was quite realistic considering the times. It did show how hard is to be a woman in that world. There were even times where Poli herself did disappoint me as a reader, but we have to consider how people see her and how they understand the aspect of women straying out of the norm they heavily reinforce all the time.
Years later Poli did call the Emperor on his behaviour when they first met, and the Emperor did apologize and behaved better, so let's not take that out.
So saying the novel was bad just because treated serious stuff in a heavy tone is not the way. It's interesting, it makes you feel bad and when Poli achieves something its so much rewarding.
And pretty much everyone was a jerk to her, Donau, her father, stepmother, father, colleagues, soldiers, noble wives and so on. Everyone likes to enforce a certain way to be a woman to Poli. They look down on her achievements, her appearance, on everything. It took her 10 years to get respected as she should (even if not completely). So let's respect that.

I AM SO GLAD THAT THE MANHWA IS 999999999X BETTER THAN THE NOVEL
The novel is seriously bad cuz when she first went to the war, She was raped and the emperor was a jerk when he took her in as he let his sub coordinates do whatever they want with her, rape of whatever . In the novel I felt so bad for Paulina because there was more suffering in the novel than in the manhwa (╯°Д °)╯╧╧