I kind of wish we had a bit more of a look at the emperor's motivation other than "I read her diary and decided I should sacrifice everything for her". There should be a lot of people who sacrificed themselves for the empire, to fulfill a role, etc, and he should be aware of it. So why is her sacrifice so impactful to him, when he seemed to care so little about her? The thing with the flowers is a nice touch, but it just shows that she was attentive of his needs and he took it for granted, it doesn't really tell us anything about him. How did he perceive her before, and how did knowing the truth make him feel guilty? Like, if he was cold to her because he thought she was power-hungry, and then he learns that she never had a choice, then I could see the guilt eating away at him more believably. Here it seems like the author just didn't want to put too much effort into the set-up. Even the narration highlights it "this story starts with the MC noticing the absence of the woman he neglected". He wants to just outline the situation then jump right into the story.