Borderline personality disorder (BPD) is a type of personality disorder that affects about 1-3% of the population. People with BPD struggle with self-image, and their behavior and view of others can change quickly as they battle waves of sadness, anger, or anxiety. According to the National Institute of Mental Health, BPD may be linked to traumatic events, brain chemistry, and family history, but these factors aren’t always present in people with the disorder.   

Hidden, or quiet, BPD occurs when symptoms of BPD are present, but internalized (Healthline, 2020). Because symptoms of hidden BPD are not displayed outwardly, it can be difficult for someone without BPD to understand that a friend, partner, or family member’s actions are due to borderline personality disorder and not a toxic personality or a different mental disorder like anxiety.   

Disclaimer: Do not use this video as a self-diagnosis. But If you see yourself with these symptoms, it's best to consult a professional.