Definitely Neighbors 2010 (South Korea), also known as Iutjip Wensoo, Neighbor Enemies, Neighboring Exes is South Korea drama premiere on Mar 13, 2010 on SBS
Married couple 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.