EFT can be helpful for almost anything, but it is extremely useful when dealing with fears, phobias, traumatic memories, and negative emotions like anger or guilt. So far the only time I have found that EFT made no difference was when the issue turned out to be of past life origin, and therefore needed to be recognised before it could be resolved (which we did with Theta DNA Healing).
"The cause of all negative emotions is a disruption in the body's energy system" The distressing memory, whether conscious or subconscious, causes a disruption in the body's subtle energy field, which then results in negative emotions and/or physical symptoms, ranging from churning in the stomach to serious illness (if the problem is left unresolved for long enough). EFT deals with the "disruption" so that you still have the memory, but it will not be accompanied with the negative emotion/feeling. You will hopefully even be able to see the posotive things that have come out of the situation.