Duty over love

One of Jon's major struggles over the course of his life has been having to choose duty over love again and again.

He decided to join the Night's Watch. He left his family for duty, knowing he may never see them again.

During his time serving in the Night's Watch, his sense of duty was tested a lot. His brother was going to war and he stayed. He killed Qhorin Halfhand, whom he admired, because he had to.

His love story with Ygritte was both legitimate and based completely on him fulfilling his duty at the same time. He had to have sex with her in the cave(he also wanted to) to stay alive and infiltrate the camp convincingly. He was in this relationship knowing he would either have to one day betray her or die. When he was put into a situation where he had to choose between Ygritte or protecting the horse breeder, he chose the horse breeder because it was his duty to protect him. Jon luckily escaped.

After the battle for the wall, he went to kill Mance, who he had grown to like, because that was his duty.

Then his sense of duty expanded in protecting the wildlings as well from the white walkers, he got murdered. So on and whatever.

He came back and went to war knowing full well he'd probably fail because he had to protect his family. When he became King, it was his priority to make alliances to protect the north and hopefully all the other people in Westeros. His duty is expanding.

He bent the knee (sort of), knowing his lords may not accept it, because he needs her to help defeat the white walkers and protect his people.

Anyway, here is my point. I think there may come a situation where he has to choose between Daenerys and duty and he will have to choose duty. He obviously has feelings and those feelings will grow, but nothing will stop him from doing his duty until the end of time.