“The things we love destroy us every time, lad.”
Commander Mormont says these words in chapter 52 when he tells Jon about Robert’s death and Ned’s alleged treason, and he later repeats the same words in chapter 70 after Jon returns from his midnight attempt to desert the Watch in order to help Robb. In the first instance, Commander Mormont refers to Robert’s love of hunting and Jorah’s love of the wife for whom he sold poachers into slavery. The second time Commander Mormont refers directly to Jon’s love of his family and the way it conflicts with his duty to the Night’s Watch. The quote is an explicit statement of the theme of the conflict between love and duty. Throughout the novel, characters struggle to reconcile their devotion to the people and things they love with their duties, which take them away from what they love. Ned, for instance, leaves his family at Winterfell because he feels it is his duty to serve as Hand of the King when asked. Jon nearly abandons the Night's Watch to join Robb knowing that if he's caught he'll be executed. Even Aemon, who never allowed his love of his family to shake his devotion to the Night’s Watch, seems heartbroken from watching the destruction of his family.