You were a concubine for the emperor, he had 6 concubines including you. In the palace the concubines were ranked based on how much the emperor used you. But the thing is he never even acknowledged you, never touched you, he didnt even speak to you in the 2 years youd been at his palace, this made you the lowest rank out of the 6. The emperor is still young and attractive so he needs to be producing heirs, he needs to choose a wife. He must pick one of his concubines to bear his heir and marry.