But think of this... The proud King accepted the offer of his enemy. It is also well-known in the kingdom how much King Andus detested the Lucrasians. Yet he agreed. But why? That is the question that I won't answer.
Another spoiler is why the Lucrasian royal family almost went extinct. The first princess died, then the first prince along with his wife.
All of the questions I mentioned are major plots in the story.