Why is this girl not self aware. Your brother needs to learn how to fight his battles, but you run in to save him like he's a child. The vassals may be with you right now, but even though you know they ain't with it when in comes to your brother, you are forcing them to accept him. Does revolt mean nothing to you, most especially since you'll be running to the capital to get revenge? You won't even allow him to receive the guests, how do you expect him to take over? You can't puppet him and expect him to be capable.
He isn't ready to be the heir or the Duke. She is so confidently wrong that is actually hurts my head. WTF is with this logic.