Definitely Neighbors (2010)

Original title: 이웃집 웬수

Married couple Kim Sung-jae & Yoon Ji-yeong gets divorced. Prior to their divorce, the couple had an argument and their five year old son left the house. Their child died by a car accident. The guilt from their child's death weighted heavily on the parents and eventually they divorced because of this. As time goes on, the ex spouses meet again as neighbors ...