Borderline Personality Disorder is manifested largely through the defense mechanism of splitting. Splitting is vacillating between the extremes of idealization and devaluation. What results from the negative half of splitting – devaluation is projection and lack of trust. A.J. Mahari, author, speaker, mental health and life coach, in a video, talks about how the negative thinking experienced in the devaluing half of borderline splitting obliterates idealization and produces a marked shift in the mood and behaviour of the borderline.