Often the chemistry between affair partners functions as a kind of anti-depressant. Clinically, the activity levels in the brain of someone in a state of romantic love are quite similar to that of someone on cocaine. Love is an intense stimulant, and quite often literally intoxicates - but the stimulation can have a medicinal quality. A person who is depressed find relief, and therefore often can't comprehend the destructive nature of their actions. They feel better than they have for some time. The depression is temporarily lifted.
“No problem can be solved from the same level of consciousness that created it. ” – Albert Einstein