I believe the correct answer is the parents' household rules unpredictably change.
For children's well-being the most important is the consistency in parenting style which is why if the household rules suddenly change in unpredictable matter children will get confused and have a hard time adapting to the new conditions. Apart from that, for the children’s well-being is also important to show love and flexibility in varying their child-rearing strategies to provide the best discipline-environment fit.