I'm not sure if it's Shoujo but it's a completed manga and it's about this lady who was a royal who had to run away from the palace because her brother(?) Or another male royal was trying to kill her. She isn't your average loyal and she knew how to swordfight and ride horses etc.

I remember it ending in her becoming the empress (or queen) and appointing the male relative of the one who was trying to kill her as the principal of a school (because she wants to keep him close and because she loves him but his previous betrayal would've caused problems).

It's in medieval historical set up, her father (king)'s brother commit treason and the brother's son is ordered to kill her. But they're actually in luv lol. The ml is being kept as a principal so he doesn't have any royal power.

There was also a scene where the female MC was in a dungeon/prison and was chained at her wrists. They cut up her dress and she was about to be raped when the male relative guy showed up and helps her escape.