I've heard a lot of people refer to "splitting" in borderline personality disorder (BPD), but I'm not exactly sure what that means. What is splitting, and how does it relate to BPD symptoms?
Splitting is a term that describes difficulty with the ability to hold opposing thoughts, feelings, or beliefs about oneself or others. In other words, positive and negative attributes of a person are not joined together into a cohesive set of beliefs.
Splitting is very common in people with borderline personality disorder (BPD), and it leads people with BPD to view others and themselves in all or nothing terms. For example, a person with BPD may view one family member as always good and another as always bad. Or, a person with BPD may see themselves as good one minute, but shift to seeing themselves as all bad or even evil the next.
Because of splitting, it is difficult for individuals with BPD to recognize that good people sometimes do things imperfectly or make mistakes. The experience of splitting is very confusing and frustrating for people with BPD and their loved ones. Splitting can interfere with relationships and work life, and can lead to intense anger and self-destructive behaviors.
Sources:
American Psychiatric Association. Practice Guideline for the Treatment of Patients with Borderline Personality Disorder. American Journal of Psychiatry, 158:1-52.

