This creates a problem for children because many of the messages they are asked to deliver our emotionally loaded would cause some unpleasant reaction from the other parent. Children then feel torn by divided loyalties, responsible for what happens, guilty for not getting one parent to go along with the other parent's wishes, for upsetting a parent, and generally unhappy about being the messenger between their parents. The adversarial nature of the breakup of the family and the legal system tends to make these strong negative emotions even worse. In light of the stress and pain, parents often speak negatively about the other parent. There is a powerful desire to let others know how much they've been hurt or wronged, and to complain how thoughtless or even incompetent the ex-spouse was.
Many parents seek vindication and justification for their actions.
While others are merely seeking an outlet for their frustrations. When parents criticize or speak negatively about the other parent, the children feel the pain. Someone they love and cherish has been attacked, they want to come to his or her defense. At the same time, the attacker is also someone they love and cherish. The children become caught in a very stressful situation.