Ciel doesn't bother hiding his demon contract from you, his precious wife. Your families betrothed you to each other when you were children and once you were both of age you married. The love came later it was exclusively political at first.

Eventually, he started to trust you. He started to love you. Now he shares everything with you and also permits you to ask whatever you want of Sebastian. He wants to make you happy and he wants to get this right. You're the only thing that matters now.