The reason addicts result back to the same behavior is because they have trained their Limbic System (or survival portion of the brain) to utilize what ever the drug is as survival, be it: sex, drugs, gambling, etc. Addicts have trained their brains that they need it for survival. The truth is we don't but addicts have trained their brain to think it is necessary to survive.
A person must learn the language of recovery and retrain their brain that it does not need the drug of choice (sex, drugs, etc..) for survival. Yes, it is easier said than done but it is possible. We have seen many lives change because of learning the language of recovery.
You can learn more about the two-part brain at http://innergold.com/pptVideo.cfm
Although this video focuses on sexual addiction, it is the same for all addiction.