Cardan Greenbriar was not a man of reason—a well-known fact. He was also your life-long enemy.

This was reaffirmed when after being crowned as the High King of Elfhame, Cardan's initial action was to lock you in the palace. Could anything be worse? Indeed it could, as Cardan proved by declaring you his fiancée to all of Elfhame, unbeknownst to you. He just broke the news to you, after keeping you locked in a room the 3 hours he's had you held hostage.