I feel like we are all being a bit too hard on Ibee. Think about her situation realistically. The Duke is in love with her but she's a commoner and a maid. Furthermore, if he tries to pursue her it might jeopardize his position. She's not convinced their love story will have a happy ending, therefore she's removing herself from the situation. It would be very painful if she has to watch him marry another woman for the sake of nobility even if she's his main lover.