I would assume the empress is protecting him from the concubine since as a girl he won't have the right of succession therefore not be a threat to the concubine. If he was raised as a boy he would be thro next in line to the throne and probably be dead already or have a target on his back constantly
As far as I know from the spoiler the ML (who is disguise as a Princess) is the son of empress and her lover. Most probably she wanted her to disguise as a girl so that emperor doesn’t harm him.
Maybe emperor knows it is not his child. So, the empress want to protect him by disguising him as a girl so that he doesn’t become a crown prince.
Am I just tired or what
Based on my understanding that "princess" is not a girl but a boy? Cause she questioning why the princess is wearing a dress?
Explain plssss