People with Borderline Personality Disorder (BPD) are not necessarily codependent, but there is a strong correlation between the two disorders. Codependency is when someone has an unhealthy relationship with another person and is overly reliant on them for their emotional needs. This can often lead to Codependent Personality Disorder (CPD), which is when someone cannot function without the other person in their life. People with BPD often have codependent relationships because they fear abandonment.