Why woman dont give secong chances in a relationship?

my girlfriend and I being together for the last 3 years, we both a house we have a 2 year old baby, and out of no where she broke up with me one night the next week she is telling me she is moving out? all because I dint help enough with the things around the house more? claims there is a wall between us and she cant pass it trough?? how is this possible is this a normal behavior in a woman? how can some one just trash a family like that? any ideas why?