Jon's purpose has always been to bring different people and factions together. That is why he was brought back from the dead. He would have never been King, as well. His story resembles Aemon's (Rightful King of Westeros not wanting to rule), and his place was in the North, with Ghost. Sad he had to leave his family behind, but it was fitting (reunion with Tormund and Ghost). Stop crying, the end was ok (not the best, had many flaws, but ok nonetheless). Besides, what did you expect, with the books no longer being there for inspiration?