Other disorders, such as clinical depression, certainly affect loved ones. But a clinically depressed person could be depression locked alone in a room. The very definition of a personality disorder, on the other hand, is that it causes distress for both the person who has the disorder and those who interact with them. In general, people with BPD feel worthless, empty, moody, needy, depressed, and have difficulty managing their emotions. BPs often act inconsistently, act impulsively in ways they later regret, see other as either all good or all bad, and base their beliefs on feelings instead of facts.
Borderlines are people in pain.
BPs who act in may mutilate themselves, make suicide attempts, express self-hate, or seek outpatient or inpatient therapy. Other BPs manage their pain by trying to foist it on others. They blame loved ones for all their problems, criticize, make unfair accusations, act emotionally or physically abusive, put others in no-won situations, and use emotional blackmail to get the love they need. People with BPD feel isolated. Terrified at the thought of being alone.