@felini As she mentioned, it was so she could have a stable unemployed life. Key point being "stable." If she simply becomes consort and befriends the future empress whom the emperor will love, then she could live a pampered life without the obligations that come with being the main wife. She probably also doesn't have to worry about producing heirs, and since she holds no feelings for the emperor then she doesn't have to worry about bedroom obligations either. If, however, she ends up becoming the wife of some other noble that she likely won't care about(and who might be twice, if not thrice, her age if stereotypes are anything to go by) then she will still have to produce an heir for said noble and will have to do wife things that she'd rather not do. (She'll probably have to do some things as consort, but it shouldn't be as unwanted or as taxing as empress or main wife to some random noble)
Simply put, she wants to live a safe life while also being pampered by her status as consort. So long as people don't misunderstand her and think she desires power, then she will be fine. It sucks when others act on your behalf when you don't want them to, especially if said people try to hurt those you're trying to befriend.