What an insightful comment; I'm ever so glad to discover a grown man criticizing a young girl for how she handles situations where she's continually abused and manipulated (who doesn't love victim-blaming, am I right?) And in the comment section for fan art, no less. Bravo.
I understand your umbrage but it if it was not for the thankful and glaring contrast of Sansa's younger sister Arya, whom the former would always belittle for her disdain of submissiveness and other courtly "virtues," your complaint would have some merit. Sansa is one of many characters that Martin uses to satirize and scathingly critique the many tropes of epic fantasy that are merely transposed from the maudlin romantic historical fictions of the 18th and 19th centuries (not to mention Walt Disney). Arya Stark, Brienne of Tarth, and Daenerys Targaryen stand heads above the other female characters of the series because they dare oppose the conventions of their societies and are prepared to risk everything to do so. As strong-willed as Lady Catelyn Stark and Queen Regent Cersei Lannister are, they still remain inside the box in terms of maintaining their status, such as it is, in their society even if they have to resort to courtly intrigue and treachery to do so. They ultimately accept the role of highborn women as political currency and urge their daughters to do so, even though, in Cersei's case, it is something she loathes.
Both Sansa and Myrcella Baratheon, who are alike in age and even developed a friendship that was not made evident in the TV adapatation, are arguably victims of the society which has conditioned them to the roles they accept. If I am unsympathetic, it's because their younger siblings, Arya and Myrcella's brother Tommen actively rebel in their own ways against what their society dictates they should be and do. That is interesting, that makes for good drama. You root for them to succeed whereas waiting for the damsel in distress to be rescued is quite frankly, boring. That's what I like about Daenerys who finds that all the courtly etiquette and protocol she grew up with is utterly useless, especially now that she holds the power and nurturance of dragonkind in her hands. Myrcella is shipped off tearfully to an arranged marriage and Cersei is crushed. So, too, is Tyrion, who thought it better his niece be safe than under the "protection" of Sir Ilyn Paine's greatsword. The unspoken victim in all this will be Tommen, who has neither the desire nor ability to be king.
Sansa does have moments of backbone but she balks and accepts a choice perhaps someone with more modern sensibilities would not. Gregor Clegaine thwarts her taking the vile Prince Joffrey with her over the castle ledge and later presents her what is her only chance to make a clean escape, which she refuses despite having fled the panic room where Sir Ylin awaited the order to dispense "mercy" should the defense of the castle fail.
Actually, and I won't spoil things in case you are not familiar with the story from the series, there is a rescuer who will be thrust into protecting her and trying to motivate her to assert herself. It will not be the unctuous Lord Baelish, whose "concern" masks the sublimated lust he has for Sansa's mother. There is still the chance that her personality can change for the better. As Hemingway wrote, "The world breaks everyone and afterward many are strong in the broken places."
I respect the hell out of Sansa. She has survived the most dangerous of situations without having one true friend/mentor (no Syrio, no Jacquen, no Yoren, no Gendry, no Kindly Man) and has had to learn quickly while doing so. With her quietly (and rapidly) growing knowledge and experience, Sansa is no one to dismiss out of hand.
And this is coming from someone who hated the Sansa chapters in the beginning.
As I said, there are glimmers that she is beginning to evolve a spine but she has yet to make that decisive step out of the cesspool of the court, as it were. I am glad they did not show the extent of her humiliations that are shown in the book. It would be too controversial with a character who is depicted as a minor.