i think he can't just say "i don't want to marry her anymore" he needs a reason and this isis is from a good family what is a reason for him not to break it of. Also everyone knows about their engagement.
Politics. They are engaged because he didn't have the power to refuse the aristocrats faction. CMIIW. They are now just fiances in name. Tho Lady Isis doesn't think so. He needs more power and support to surpress the nobles before breaking off with Lady Isis. I think.
They are not engaged, isis is from a powerful family so everyone and isis are imagining that she would become the crown princess. That's why asterope got mad when isis yelled at him for being with aria during the bday party
They aren't engaged. Isis family is just powerful/corrupt family that all her faction assume she will end up being the Queen. Also because the prince is laying low profile all of them think they are in control.
Why is he still engaged? Like ngl if you have a fiancé your chances of getting the girl you like tend to be lower