Confessing My Love to Him, the Treacherous One - Chapter 29

I sincerely hope that later on in the story, they explain why the king/emperor, or whatever his position is, did not just force Charles to marry his daughter. Why go through all this, so he can make a choice to continue to not marry her? What are they gonna do if he just chooses to remain unmarried and they both grow old? Is it just a if I can’t have him no one can deal? I know the plot has to plot, but I just need a little bit more explanation.