It's a scary thing to watch when this happens to a loved one or friend. You feel helpless in how to help them. If you say anything, the abusive controlling person will even try to turn them against you!
Stockholm Syndrome in relationships is not uncommon. Law enforcement professionals are painfully aware of the situation – making a domestic dispute one of the high-risk calls during the work hours. http://drjoecarver.makeswebsites.com/clients/49355/File/love_and_stockholm_syndrome.html