People (including myself) more than often develop repetitive patterns because it's familiar. They know what results to expect and how to deal with it. FEAR prevents us from breaking the cycle. If it's someone that you know caught in a repetitive cycle, the only thing you can do is make them aware and be supportive.
However, you will have to ultimately make the decision and say when enough is enough. Sometimes this happens due to a forced changed or just being plain tired.