Accept

The idea of having your sister pledge to this man's lust isn't appealing, but the Arch Duke is right. If he or someone managed to convince the King of Francia to agree, the resulting treaty is more than what is typical for giving your sister to a man. And not to mention that you both still know that you need the Arch Duke's loyalty right now more than he needs you.

With one last bit of consciousness, you ask, "And what about my dear mother and your soon-to-be wife?"

You watch as Arch-Duke Wilbur grins when you mention her before he says, "Well, in order to keep our public image, I would still be marrying her. But since I will have her daughter, I will no longer require or want her in my bed, so you are free to take her whenever you desire her."