The episode was beat of harsh but at the end dany believes in jon. Talking about the Wight walkers their army became strong and nearly unbeatable. The main problem occurs in winterfell because of the littlefinger. The both sisters were opposed each other and their faithfully ally lady Brien is marching westroes. There is no one there to advise them. Sansa is like her mother but her decisions lays on littlefinger. We all know sansa wrote that letter back in season 1. However littlefinger found that. They make jon king in the north and they trusted jon but he is not there. Northerns are come together to fight against army of dead, but this letter will change the prospective against house stark.