It's an old truth of fiction: if you want to make a female character suffer, rape her. If you want to make a male character suffer, rape a female character he cares about. And rape is pretty much the default threat in most genre or "gritty" fiction. I read mostly young adult fantasy, and almost every single one I read features at least a small throwaway scene where the protagonist is threatened in this way.
This is almost invariably treated as a terrible threat, as it should, and rape victims in the majority of stories I read are treated with great sympathy. But in the quest for Strong Female Characters, for a way to give protagonists "empowerment" plot lines, some writers have been using the rape trope in a different way, using it as the impetus for that transition from "weakness" to "strength."
Let me be clear: there is nothing wrong, theoretically, with the story of a rape survivor finding strength. Rape is a too-common reality in our world, and no one should take those sorts of stories away from readers who might be comforted and inspired by them. But there are certain trends in these stories that are unsettling, suggesting that this story of strength from trauma is less about the character themselves, and more about the difficulty writers have balancing the one-dimensional conceptions of the damsel and the Strong Female Character.
Basically, it's the inability to consider female characters complexly. Strength is not seen as a property of characters like Sansa Stark, who embody stereotypically female traits -- who are pretty, who aren't tomboys, who like romance and dresses and might be more than a little naive. Character who don't wield swords, will never wear armor, who are generally earnest and kind-hearted. Female characters can have strength if they're the tomboy, fighting sorts, or if they're sexually manipulative, but innocence can't develop into strength, because these softer traits aren't seen as strong, and female characters certainly can't have a mix of characteristics.
But feminine characters, we've been told, are bad. This "weakness" is bad. They must be "strong," a strength that many writers imagine with a similar lack of complexity. And they must be changed, fundamentally changed, in order to fit that idea. It wouldn't be enough for her to simply become more determined and independent, and it wouldn't be believable for her to switch from kindness and innocence to that violent conception of strength. The writers need an impetus.
And what better symbolic impetus of that change from innocence and weakness to coldness and violence than rape? What better than something that is seen to literally destroy innocence, that shatters them emotionally and changes their entire view of the world, so that they can become, in part, the violence that they have suffered?
There is no proof yet that this is where Sansa Stark's plotline will go. But the discussions of this being the season of her empowerment definitely hint at such a story.
And through it all, there is the strong implication that "strong" and "feminine" don't go together, and that such a female character cannot empower herself. She must first be deconstructed by trauma, her innocence ripped away, so that she can be rebuilt as someone "strong" -- someone not just with resilience, but a different woman than before.