Will Sansa learn in TWOW of fArya's marriage?

[Nevets]

I think it is almost certain that she will find out about Ramsay's marriage to "Arya".  The Starks were quite popular in the Vale, so news about them would likely be a popular item.  She could hear about it from Myranda, or overhear somebody else talking about it.

What she does next is unclear.  I would guess that she would assume that it was the real Arya, and that the Lannisters had somehow managed to either keep her or find her.  She could ask Littlefinger about it, but might not, especially if she doubts that she will get a truthful answer.

I doubt that news about FArya's escape has gotten widely distributed.  The Boltons certainly don't want it getting out, and it will likely take time for news to get out from wherever she winds up.

If Sansa were to find out about Jeyne's mistreatment, I imagine she would be quite angry.  It could even result, or help result, in a breach with Littlefinger, which I think is coming in the not too distant future.

[Nevets]

1 hour ago, Therae said:

He's had Dontos killed as a reward for getting Sansa out of King's Landing, explained that his plan involves framing Tyrion for Joffrey's murder, so T would be executed and make her a widow, also explained (albeit, not in so many words) that as a result of his assassination plan, Sansa herself is on the hook for it and now depends on him for safety, told her he slept with her mother, implied that he didn't think much of her father, killed her aunt right in front of her and framed Marillion for it, told her he planted a mole in the Lords Declarant, and stated flatly that Sweetrobin won't survive very long--after initiating the process of poisoning him, and, so far, none of that is leading her to mistrust his intentions, even though she's uncomfortable with his Creepyfinger kisses and touches, but what he has done to Jeyne could actually turn out to be the thing that makes her go cold on him. I sure hope so.

When Littlefinger killed her, Lysa was in the process of trying to kill Sansa, and might well have tried again.  Marillion was also an ongoing threat - to Sansa and every other female in the Eyrie.  I expect that Sansa may be relieved at their passing, if not necessarily the means.

She figured out for herself that there was a mole in the Lords Declarant, although LF did confirm it - and seemed pleased that she had figured it out.

Everybody expects Sweetrobin to die soon.  Even Jaime said flatly that he "wouldn't live long enough to breed", and I don't think he was concerned about homicide.  The boy really is in poor health.  And if he is being deliberately poisoned, Sansa is surely unaware of that fact.  It is worth noting that Sweetrobin's death at this point would be quite inconvenient for Littlefinger, although it is quite possible that he is deliberately being kept in a weakened state.

And, as other have mentioned, Sansa does not really trust Littlefinger and never has.  It is just that she has no other options at the present moment.

[Nagini's Neville]

1 hour ago, Therae said:

@Nagini's Neville - all good points. It's just my take is the one thing we really see giving her the pause about Littlefinger is the icky molesting he does. It's the only specific thing she's reluctant about. The quote you've used doesn't question any of the actual horrible things she knows he's done; basically she's realizing that he has not let chivalry get in the way of his political standing when there were opportunities to help her and show her some kindness. I think she knows he isn't doing whatever he's doing out of good, clean, wholesome love for her poor murdered mother, or herself for that matter, but she doesn't seem to question his methods--or at least she is very good at suppressing thoughts of that kind and/or rationalizing them. But, as I said, I think what he's done to Jeyne could be the thing that breaks her from him.

I think she does to an extent question his methods or at least is appalled by them. She was really shocked when he kills Dontos and tells him that Tyrion was kind to her (or something like that). But the problem is that through her trauma in KL she might have been a bit to disillusioned now. Everyone has treated her so horribly and has betrayed her every step along the way, people have been cruel and ruthless, she has experienced herself that nobody she encountered truly was honorable and trustworthy not only concerning her, but other people as well. LF gives her some valid reasons for why she shouldn't moan Tyrion (because he let his first wife be gang- raped) and all Dontos did was sell her out and he had to be killed otherwise he'd do it again. Sansa is absolutely shocked, when she hears, that Dontos wasn't her Florian after all. I think at this point she has given up on all of her prior beliefs in how the world works. And if Dontos lied to her the whole time and would have possibly sold her back to the Lannisters and Tyrion gave his wife to the guards maybe what LF is doing and the way he is doing it is just the way this world works and necessary after all. Non of the songs are true. Everyone is corrupt, because the world doesn't leave you a different choice. “Is it all lies, forever and ever, everyone and everything?” She is questioning her world view again. Maybe she starts to question, if all that the Hound told her was true all along. "

"If there are gods, they made sheep so wolves could eat mutton, and they made the weak for the strong to play with.” (...)If you can’t protect yourself, die and get out of the way of those who can." But IMO she is not completely convinced of that yet, but I think she is filled with doubts about everything and everyone including LF. Because if everyone is a liar all the time (“ "Is it all lies, forever and ever, everyone and everything?” “Almost everyone. Save you and I, of course.” He smiled.") that surely could include LF as well and she is aware of that.

When it comes to Lysa, Marillion and Sweetrobin I agree with what @Nevets said. 

I also don't see, how her mistrust in him should only be rooted in him molesting her. I personally don't think, that's apparent from the quotes I provided. IMO her feeling in need of protection is the result of the the combination of everything she has witnessed him doing.

Here another quote of Sansa knowing LF is lying to her and questioning LF'S methods:

"He is serving me lies as well, Sansa realized. They were comforting lies, though, and she thought them kindly meant. A lie is not so bad if it is kindly meant. If only she believed them … The things her aunt had said just before she fell still troubled Sansa greatly."

AFFC, Sansa I

[Therae]

@Nagini's Neville - I'm not sure if you and Nevets are reading my take as criticism of Sansa--that's not what I'm trying to communicate. I realize she understands that many of the horrible things LF does have protected her, whether that was actually his main goal, nice-to-have, or a happy accident. My point is that he's done a lot of horrible things that she knows about firsthand, and she is able to consistently find ways to work with him, mostly by not thinking too much about any of the many things that strongly suggest he will not hesitate to ruin a life or end it altogether if it suits his purposes, but that Jeyne may be where she draws the line.

Yes, she knows Littlefinger serves Littlefinger, she knows she doesn't really have options, and she does think about them from time to time. Sansa has never actually been all that complacent in her head. She did, after all, consider pushing Joffrey to his death when he showed her the heads, and she spoke up to him on plenty of occasions. And I don't doubt it's as a result of what she went through in King's Landing that she has taught herself not to think too much about what she can't control. She sees them in the moment, notes them, has her misgivings, and accepts the situation, one way or another, whether because she can find a rationale for the things he does, or because she doesn't have anywhere else to go, no matter how self-interested and sleazy she knows Petyr to be.

She does not, however, ever get comfortable with his advances, anymore than she did with Dontos, which is why it stands out to me. She's willing to pretend to be his daughter. She's not willing to be his secret babyCat or whatever barftastic relationship he keeps trying to draw her into. Truth to tell, she doesn't think too much about that, either, when she can help it, but I always get a vibe of revulsion in those moments. It's totally possible that's my own vibe of revulsion, but I think we're supposed to understand Sansa does not think it's okay. I don't know why Petyr keeps it up, either, since it appears to be clear to him that she's put off by it.

In any case, I am not trying to say Sansa is stupid or bad or an incomplete person because she knows that Littlefinger has done a lot of terrible things, several of which have directly kept her from harm and she doesn't turn on him. I'm trying to say that if she finds out about the terrible things he has done to Jeyne, I expect she will turn on him.

[Nevets]

It has occurred to me that if Sansa finds out about the marriage, it would cause her to further distrust Littlefinger.  She would most likely assume that it was the real Arya.  If so, then the Lannisters would have had her all along, or had managed to recover her. Either way, Littlefinger would have had to know.

While she might distrust him, and be inclined to disbelieve anything she is told by him about the marriage, I can see her asking just to see how he responds.  If he does tell her it's really Jeyne, it will be interesting to see how she reacts.  

In any event, while I doubt she knows anything about Ramsay specifically, the Boltons do have a very sketchy reputation, and I expect that she would know that much at least.

As to what could cause her to turn on him, I can think of numerous possibilities, of which Jeyne's mistreatment is prominent, as well as his actions towards her parents, and his apparent poisoning of Sweetrobin.  Not to mention stuff that could happen in the future.  I expect her takedown of Littlefinger will mark her arrival as a player.

[Rose of Red Lake]

She has to learn about Jeyne eventually, they are too connected storywise. I'm hoping that because she has free access to his office she might find some correspondence that gives her a clue. LF is getting careless.

[The Sleeper]

As mentioned, in the normal course of events she will. This is an important event. It will become public knowledge. Littlefinger could contain the information for a time, by telling the maesters no to announce any news they receive from the outside world but eventually someone would come by who share his news about the marriage with castle. There two ways that this event would be kept from Sansa indefinitely. Either she is removed from the Gates of the Moon to a place with no regular outside contact with the outside world, or if the Gates go on lock down. 

I don't see any particular reason why the information threatens LF in regards to Sansa. Sansa would only learn of Arya's marriage to Ramsay. She has no way of knowing Littlefinger's involvement in that affair and Littlefinger is unlikely to tell her. He has the liberty of presenting this in whatever context he so chooses. My money is that he is going to present the bride (whether he reveals her to be Jeyne or not) to be complicit to the marriage in order to steal Sansa's birthright.

As for involving him in his crimes, I believe it is quite deliberate. In this fashion it makes an accomplice, a conspirator both in her own mind as well as others. This is patently effective; Sansa is reluctant to declare herself to Yohn Royce fearing her implication in her aunt's murder. He shares only the parts of his plans that directly involve Sansa and what she can directly observe. He involves her making her complicit in deed as well and giving her the illusion that he means for her to be more. All of this is aimed at making Sansa utterly dependant on him. As it is, there is a good chance that if LF goes down Sansa will be going with him. 

Littlefinger is doing all that, because at the end of the day he is not that original. Lysa was his original vehicle to power, Sansa is being groomed to take her place and help him cement his position in the Vale.