Two addicts or alcoholics in a romantic relationship are like gasoline and fire. The passion runs high on the positive end and on the negative end. Often times these relationships are filled with psychodrama and vicious arguing. Two people involved in such may be experiencing a certain "emotional hemophilia" in which the fighting continues, things cannot be talked about logically and brought to a resolution. this is often a direct result of the swirling vortex of addictive insanity in each person as well as a plethora of character defects in which each person wishes to have the last word.
Senseless fighting can lead to an increased level of emotional discomfort which will most likely be medicated by the addict/alcoholic. The potential for ultimate destruction exists inside these fights.
One way to have the last word is to say "I'm sorry." Holding onto that and not starting the fight again is the work done inside the 12 steps.