The reason why he let's Diana poiter (or whatever) get away with everything is because he has mommy issues and feels pity towards her mother who suffered in the hands of the previous empress BUT the target for his Oedipus complex was not his biological mother for whom he only feels pity but the empress who he thought was his birth mother and didn't understand as a child why he could never get her approval and affection which got twisted as time went by. after discovering his true birth mother and understanding empress's contempt towards him and his mother his love/hate relationship with her grew even more twisted and the reasoning for his hatred (more like an excuse in his head) became her bullying his "real" mother but in reality it's that he could never get empress's approval.
After Diana's appearance he felt pity for his mother not only because the things she endured but that he never truly loved her like the empress and tried to Chanel that guilt in to his relationship with his mothers copy paste clone but we can clearly see that he has no actual romantic affection towards her.
After MC appears she started reminding him of the empress, he hated her guts and wanted to subdue her at all cost which we can clearly see in chapter 25 where he admits it, in other example when MC goes to his room for consummation of their marriage he instead humiliates her and gets immense enjoyment out of it because this way he got her attention. Also gets jealous of her aid and so on and on there are lot of example of his obsession with the empress and later on MC.
So my (obvious) prediction of what's going to happen is he gets more obsessed gets tired of Diana and mistakes his desire to fuck his mom (again) for love at which point our dear MC gets tired of his shit and chooses the aid (thank god) divorces him or something and hopefully lives happily ever after, but for me personally I would love it if she usurped her brother and took the throne for herself.
Sorry for my limited vocabulary, English is not my first language and I'm terrible at spelling thank you for patiently reading my rambling
Love this author
what’s the authors other works?
"Talk to me" and "polar attraction"