Sansa: “I can’t go. I am supposed to marry Prince Joffrey. I love him and I am meant to be his Queen.” Myrcella: “I love Trystane. I’m going to marry him and I am staying right here.” Wars are easier then daughters
The revelation of Ned’s Promise/Lie is based on GOT Fan Theory: R+L=J Ned’s mysterious promise to his sister is that he will protect her secret love child, with Rhaegar Targaryen, from his best friend King Robert Baratheon who wants to kill all.