A major effect of hormonal imbalance is drastic emotional instability.
In most cases, Emotional instability causes distortion on one's rational thinking. That explains, why people make wrong decisions, when they are emotional.
One way of thinking holds that the process of decision-making is (or should be) rational: a formal process based on optimizing utility. Rational thinking and decision-making does not leave much room for emotions. In fact, emotions are often considered irrational occurrences that may distort reasoning.