After marrying into another royal family, write a dialogue where the queen catches the unhappy princess trying to escape out the window. Make the queen's reaction surprising and supportive. She, too, is seeking freedom from royal society and marriage.
Queen: You did seem rather strong when you launched that cricket ball over the hedge.
Princess: Your majesty, I must apologize.
Queen: He is a brute.
Princess: You'd call your own son a brute?
Queen: Takes after his father.
Princess: I'm sorry.
Queen: The horses are faster than your feet, though I don't doubt you are a strong runner too.
Princess: They will see me leaving.
Queen: They will not. Go left, then right, and down the stairs. You'll smell the stables before you see them. I often sought solace there before the prince was born. Don't give me that pitying look.
Princess: My apologies, your majesty. But, why didn't you run, too?
Queen: I had no one to run to. I take it you do not either.
Princess: No, your majesty. My father would not take me back after such a disgrace, and my siblings are all bound into marital duty themselves. The duty of returning me would be their natural recourse
Queen: So, you have nowhere to go, and yet you do not want to stay here. I don't wish my life upon you, but I do know that a woman without the anchor of a man's arm will be cast off in the sea they've created. You are smarter and stronger than I have ever been. I have a proposition. I need a new stable hand. You will marry the prince and when you need cover, you hide in my employ. He does not like horses and the stable hands are loyal to me.
Princess: Your Majesty—
Queen: Prim.
Princess: Oh, I—
Queen: Call me Prim. I will be your place to run to, and if there is an opportunity, I will make a place where we can both be free.