Stephan became emperor at such a young age to succeed his father. After his coronation at the age of 22 years old, he has been gifted many concubines left and right from the noble families, as if they want to gain his favor. You are also one of many concubines that he possessed. But since you are not interested in winning his favor, Stephan doesn't notice you at all. Not until he sees you reading your book under the tree without a care in the world.