According to Reddit user Gnargiela , "every Stark that has broken their word or honor has died violently." And, well, the facts back this up.
First of all, way back in season one, hand of the king Ned Stark drew the wrath of the Lannisters when he questioned the legitimacy of the heir, Prince Joffrey. He later lied and admitted to treason in order to spare the lives of his daughters, and was executed.
Then there was his son, Robb Stark, who promised to marry Walder Frey's daughter in a political alliance, then reneged on that agreement when he fell in love with Talisa, married her in secret, and conceived a child with her. And we all know how that turned out; Robb, Talisa,and their unborn child were all murdered at the Red Wedding, a slaughter orchestrated by a vengeful Frey with a little help from the Lannisters.
Robb's mother Catelyn Stark also died at the Red Wedding. Catelyn, who always harboured resentments towards Jon Snow, who she believed to be Ned's bastard son, had previously revealed that she once prayed to the gods to save Jon's life when he fell ill, and promised to love him as she would her own child if he pulled through. She later failed to live up to that sacred oath, and got her throat cut.
Even Ned's sister, Lyanna Stark, who died before the show began and has only been shown in flashbacks, seems to have suffered the Stark curse. Lyanna was betrothed to Robert Baratheon, but married Rhaegar Targaryen in secret and gave birth to Jon. She died moments after he was born.
So how does this apply to Sansa?
In episode four of season eight, "The Last of the Starks," Jon Snow reveals to Sansa and Arya that he is Aegon Targaryen, the true heir to the throne. He swears both of his sisters to secrecy, but Sansa, who has always questioned Daenerys' competency as queen, tells Tyrion the truth. This leads to him telling Varys, which may well in turn lead to a treason plot against Daenerys. We've already seen how cold Daenerys can be when dealing out punishments, and we wouldn't put it past her to dispatch Sansa with a single "dracarys."
The same logic could be used to predict that Jon Snow will also die. He shared his true identity with Sansa and Arya, despite Daenerys begging him to keep it a secret. An insistence on following his own code of honor, even when in defiance of his monarch, is a trait that Jon has always shared with Ned Stark. Amid eight years' worth of bloodshed, perhaps the real tragedy of Game of Thrones will be the Stark family's repeated failure to learn from the past.