Why did North Korea’s Kim Jong-un spare his aunt?

The aunt of North Korean leader Kim Jong Un has survived her husband's downfall and execution, and was named to an ad hoc state committee over the weekend. The reason behind her survival is not Kim’s magnanimity but is instead due to a promise she made to Kim Jong.

Kim Jong with his aunt

Yi Kya Hui, the aunt of Kim Jong was spared after she promised not to nag the boy blunder over the growing size of his waistline. It seems on a prior occasion, at a family gathering, Hui replaced the photo of Kim Jong on the family dinner table with that of a polar bear. Kim Jong was quite distressed seeing the pic. He was more annoyed when Hui while giggling stated that compared to Kim Jong, the polar bear appears to be malnourished.

Kim was so angry that day that he only had one bottle of Nutella as compared to the 7 he has for dinner. But later on, when threatened, Hui offered to mend her ways and promised Kim that she would never discuss his weight, ever.  That statement appears to have saved her from imminent execution.