Post natal depression arouses from the female realisation that shes been tricked into replicating beta male genetics. Via typical beta male strategys - time spent, familiarity, submission, acts of service etc - she was tricked into replicating weak male genes. She didnt love that guy, but hes just always there and always trying - and she slipped up. She hates herself for this mistake. This is why women in "happy marriages" get post natal depression and women who have 3 week flings with sports stars never do. Because although the star barely replies to her and he doesnt see her - at least she birthed a warrior. Remember - 1% effort from a killer is worth 1000% effort from a man he could kill. Always will be. Genetics rule all.