Whether in moods or relationships, instability is a hallmark of BPD. The person may have wide mood swings, switching from effusive praise and love to intense criticism and blame. In moments of anger, they may do things like scream at you in public, hit you, or harm themselves—things that other people wouldn’t do in the same situation. A fear of abandonment may manifest as constant, clinginess or manipulating a relationship you have with someone else. If the person demonstrates these behaviors as a pattern, they may have BPD.
Here are a few more clues to look for in the person’s words, emotions, and behaviors that can identify borderline personality disorder.