Battle for Happiness S01 E04 Episode 4

"She died for someone's happiness."

Mi-ho is clumsy in everything about childrearing, and she doesn't fit in properly with other moms. Na-young shows hostility towards Mi-ho and Mi-ho learns from Ji-ye that Yu-jin had a grudge against Na-young in her lifetime. After Mi-ho witnesses Na-young's serious delusional jealousy that doubts her husband's conduct, she finds a picture of Tae-ho's affair in Yu-jin's house.