I disagree, he became allies with the iron king way before even meeting the Silver king and I think it would be dishonorable to just change side which she never asked him to do anyway. As for the assistant he was good at his job but he is a double agent willing to betray her for khun if he had asked so he was not completely loyal to her. As for the fiance she only agreed to be his fiance because she knew that it would come out he was illuminate and they would break off and so her mother would leave her alone about it. However he does not know this so that is bad on him. Her mother is the one isolating her she is just starting to venture out and she is trying to do it on her own which will take a while to really gain allies he's not keeping her from doing that. He wants to court her yes but she has a choice to say no.
Even if she gets the ducal family support, she will become nothing but a pawn to the red king. Because she doesn't hold the influence, it's all red king behind the scenes. In my opinion, khun's decision might be a little selfish but it works well with silver king's future. If she were to marry the good for nothing, she wouldn't be able to lead the country to her fullest capabilities. As you know, khun has been there for her and show her how real life outside the palace is. She was raised cooped up and protected behind the walls and doesn't know anything about the outside. Thankfully, after meeting khun her views change and she begins to become a better person suited to be a leader
I don't think he took the assistant cause he was jealous, he isn't an idiot like that. I think he did it cause he didn't want her or her brother to think he send this assistant aganist her to spy on her and if she find out she will be angry with him. he does not want to hurt her this way, the opposite, he wants the best for her by not be able to "spy" on her and let her do has she wish.
and no he can't just "leave" the friend he already promise to help. it does not work like that just cause he is in love with her, he still have a duty to help her brother. that won't change and there is nothing with it. yeas he does not want her to marry someone else, and if we be honest, she does not want to marry him either.
I may be the only one, but I don't really like khun. She has the potential to become empress, especially since she is already a different self than the one in her dreams. However, Khun still works for the iron king, planning to make him emperor, all while courting the silver king, probably in hope of marrying her. He tries to break off her engagement, making sure he keeps her for himself, and at the same time, taking away the support she would gain from the ducal family. She had found a great assistant who did his job properly and was not corrupt, and Khun ordered him to resign, because he is jealous, but at the same time again, taking powerful people away from her side. I am not seeing a great man while reading this, but a manipulative one who isolates the silver king so all will work according to his plan : the iron king will become emperor and the silver king, Khun's wife. If he truly loved her, he would support her in her dreams and ambitions, not work against her.