Parent who alienate have serious unresolved personal issues.
"What causes a parent to want to damage the relationship of their own child with the other parent at their own child's expense? Intentions differ from one parent to the next, but psychologists have suggested the following as potential motivators:
* An alienating parent may have unresolved anger toward the other parent for perceived wrongs during the relationship and may be unable to separate those issues from parenting issues. * An alienating parent may have unresolved issues from their childhood, particularly in how they related to their own parents, which he or she projects onto the other parent (whether or not it's factually accurate). * An alienating parent may have a personality disorder, such as narcissism or paranoia, which makes him or her unable to empathize with the child's feelings or see the way their behavior is harming the child. Such personality disorders may also make the alienating parent more likely to be jealous of the other parent's adjustment to the breakup and cause the alienating parent to have extreme rage toward the other parent. * An alienating parent may be so insecure as to his or her own parenting skills that he or she projects those concerns onto the other parent, regardless of reality. * An alienating parent may be so wrapped up in their child's life that he or she has no separate identity and sees the child's relationship with the other parent as a threat. * Sometimes new spouses or grandparents push the alienating parent into inappropriate behavior for their own inappropriate reasons, and the alienating parent isn't strong enough to resist them."