Jon Snow has long been one of the most noble characters Game of Thrones. He's the one who is most dedicated to saving Westeros from The White Walkers and is the only man after Khal Drogo to win Dany's heart. He is The King of the North and is loved by his men. But will that be enough for the coming days?
As we all know, poor Jon Snow is a bastard, so he has no claim to be Lord of Winterfell, leaving Sansa Stark the Lady of Winterfell. Supported by everyone's favourite many faced assassin Arya Stark, Sansa is Jon's biggest ally in the North and is the one keeping the motto of "A Stark must Always be in Winterfell" alive. Or, is she? Remember, she was wed to the vile Ramsey Bolton and while turning that monster into puppy food was certainly an effective way to become a widow, their marriage in the eyes of the law is still legitimate. This would make Sansa a Bolton, not a Stark. Meaning that technically, a Stark is not ruling Winterfell.
This is where Jon might be forced to make a difficult decision. After Bran refused to become the Lord of Winterfall so that he can follow the path of The Three-Eyed Raven, the only other Stark is Ayra. However, she seems a little more interested in filling out her kill list as oppose to becoming Lady of Winterfell. While currently it is unclear whether or not a Stark ruling Winterfell gives the North some special magical protection from threats, the Northern Houses are a superstitious and traditional lot and will want their traditions upheld.
So, imagine you're Jon Snow in this regard. What do you do? Well simple, you just say as King of The North you deemed Ramsey and Sansa's marriage was illegitimate and Bob's your uncle. Hold on a minute there. Ramsey and Sansa got married in front of the God Tree. This Tree is vital to the Old Religion of the First Men. The Northerners are proud to have kept this religion alive even with the rise of the Faith of the Seven. If Jon claims the marriage was illegitimate, he will be spitting in the face of the Houses that crowned him King of The North. Not something you want when you need their armies.
Also, Sansa is not a Military Leader. She knows nothing (I didn't do that on purpose, I swear) about leading men into battle. Winterfell is what holds the entire North together. Jon cannot risk losing the castle to The White Walkers, else all of The North will crumble with it. Jon is the only person who can rally all of The North together. To win, he needs to be the Lord of Winterfell.
This means Jon only has one option open to him. Now that he's bend the knee to Dany, she can legitimise him as a True Stark. He would then be the rightful ruler of Winterfell and demand that Sansa cannot rule as she's a Bolton. This puts him in the strongest position possible, surrounded by men who love him and with Dany keeping Cersei busy in The South. Let's face it, everyone knows she's gonna betray them. If he was to do this though, it would mean betraying the only family he has left. However, if it saves the world, is the price not worth paying?
Do you think Jon Snow can bring himself to betray Sansa? Do you think he'll take The North for himself? Or does he have his eye on a much bigger prize?