Why did Jonas run away?

In order to release memories into the community and give the citizens a chance to mature in the same way that Jonas has matured over the past year, Jonas will leave the community forever. This is the move toward Elsewhere that he had thought release involved in the first place. The Giver, for his part, plays a pivotal role in this plan by choosing to stay and act as The Giver for the whole community rather than only for Jonas. In this way, The Giver will atone for his past mistakes and help the community learn rather than allowing it to return to the old ways. Thus far, everyone has referred to Rosemary as the failure of ten years ago, but in one sense, The Giver is the own who failed, missing his chance to help the community learn from the experience because The Giver at the time was lost in his own grief.