This manga has beautiful art and a interesting concept, but the characters just fucking murders it, by making it look like imprisonment is something that is charming. The only character that gets a pass is MC, because, even doe she doesn't do anything except running away, she has a great motive for doing so.
My Theory
I think the reason why she doesn't try anything else then running away (like hitting the Prince) is because she has learned, over the 10 years in training, that it is useless to cry, or go against something, except running way, as that was the only way the get some peace.