This is how you make your son hate his future wife and his future wife hate him in turn. Jennette IS his family. She is the bringer of prosperity. It's awful that Roger is trying to drill into a boy's head that it's okay to disregard the feelings of a woman and neglect her emotionally if it's for the good of the family name. Cause once Jennette is Empress and Ijekiel prince consort, it's payback time. She could turn the tables on him and treat him like he treated her. He doesn't seem to quite realize it, that although Jennette is now a little girl dependent on his charity, one day she will become the ruler of a nation and would wield incredible power. She wouldn't be beneath them, they wouldn't even stand eye to eye, she would stand above everyone else. Roger understands that she is the key to power for his family, but he doesn't seem to comprehend that her lifting his family above the other won't mean they would rise to the same lofty heights as her. He is in a way sabotaging what could have been a loving marriage between two spouses who would support one another and show each other mutual respect.
I really want to know what Roger's relationship to his wife was like, if he thinks this is an acceptable way to treat your partner. Was Duchess Alpheus so kind and forgiving and self-sacrificing that Roger took her humility for granted? Is this why he thinks a little girl expressing her fear of abandonment and loneliness, and clinging onto her big brother figure, is something that could be called selfish? Why does he seem to discourage affection between Ijekiel and Jennette and would rather Ijekiel would view Jennette as a tool?
Roger is really shit at the grooming two siblings to be romantic partners thing. Ijekiel seems to do all the hard work and he doesn't even genuinely enjoy it. Novel Ijekiel acted like he was programmed to fullfill Jennette's commands against his will and hated every second of it, but it turns out Roger is really unskilled at manipulation to such a degree and even tells Ijekiel "hey you don't need to listen to her, you are the most important to me". It's really mind-boggling that Roger had this grand-master plan of making Jennette dependent on Ijekiel and having them marry, but only succeeded at isolating her and making her lonely & miserable, completely forgetting the love-bombing part that is supposed to make her ask for the marriage. It's just a coincidence that Ijekiel turned out handsome and popular enough for Jennette to fall for him in the lp timeline, when Roger didn't move a finger to set up dates for them and trigger events that would make her see him in romantic light and desire him as a future partner.