Where Jon Snow Picked Up "Love Is the Death of Duty" and Why It Means So Much to Him
Over the course of Game of Thrones, Jon Snow has been faced with a lot of choices. You could really say that about every character, but Jon's choices all boil down to a very similar theme. As a sworn brother of the Night's Watch, Jon Snow had a very ancient, very respected honor to uphold: when you take the black, you vow to give up your titles, hold no lands, father no children (which many take to mean that you must also remain celibate). Of course, Jon is one of Game of Thrones' most idealistic characters, which is why it's always nearly impossible for him to make the choice between what he wants to do and what he should do.
In the show's finale, Jon is faced with yet another seemingly impossible choice. When he meets with Tyrion in his temporary prison cell for freeing Jaime, Tyrion urges him to do what they both know is the right thing for Westeros. No matter how he feels about Daenerys, Jon's gotta kill her. Of course, Jon loves her, both as a lover and as a family member, and in a moment of clarity he mutters, half to himself, "Love is the death of duty."
Tyrion, impressed, asks if he made that up on the spot. But Jon explains that it's something that Maester Aemon once said to him, years ago, when he was faced with another impossible choice. The moment occurs all the way back in Season 1, Episode 9 (yes, in "Baelor"), when Jon is forced to make a decision between abandoning the Night's Watch and traveling south to join his brother Robb in his war against the Lannisters, or keeping his vows and continuing to serve his higher purpose at the Wall.
"Did you ever wonder why the men of the Night's Watch take no wives and father no children?" Maester Aemon asks him. "So they will not love. Love is the death of duty." Jon tells him that his father, Ned Stark, would do "whatever is right, no matter what," if faced with the choice between his family and his honor, and Aemon replies that most men are not Ned Stark: "What is honor compared to a woman's love? What is duty against the feel of a newborn son in your arms, or a brother's smile?"
The choice Jon makes in that moment -- the choice between his brother and his honor -- will haunt him for the rest of his life. After this, Jon spends a lot of time breaking the rules: he slept with Ygritte, fraternized with the wildlings, allowed them to cross the wall and ultimately join the Night's Watch, despite the protests of his sworn brothers. He later tries to amend things when he swears his fealty to Daenerys, refusing to break that vow even when Cersei offers them the support of her army against the White Walkers. For a while there it looked like Jon was the next Ned, his honor-blinders making it more and more difficult for him to see the big picture.
When it finally came down to it, the biggest decision Jon had to make was a decision he'd made a thousand times before. In killing Daenerys, Jon has to give up on love to do his duty to Westeros -- but he also has to ignore his duty to his queen to protect his family. Tyrion inverts Aemon's statement, saying that, when you think about it, "duty is the death of love." You can never have both.
The full quote, from George R.R. Martin's A Game of Thrones, ends with, "We are only human, and the gods have fashioned us for love. That is our great glory, and our great tragedy." Rhaegar Targaryen started this whole catastrophe by betraying his honor for love: marrying Lyanna Stark and fathering a child despite his duty to the realm. Jon Snow corrects this sin with a sin of his own, betraying his vows to save the ones he loves the most. The wheel of Westeros' great houses warring for power may have been broken at last, but the bigger wheel, the inevitable cycle of love and death and honor that Game of Thrones is built on, keeps on spinning into a faraway spring.