Final answer:
Feeling uncomfortable when not the center of attention and alienating friends by demanding excessive attention are symptoms of histrionic personality disorder.
Step-by-step explanation:
The symptom that exemplifies histrionic personality disorder is when Phoebe feels uncomfortable when she is not the center of attention and has alienated friends by demanding excessive amounts of their attention. Histrionic Personality Disorder is characterized by a pattern of excessive attention-seeking behaviors, including inappropriately seductive behavior and an excessive need for approval. People with this disorder are often seen as dramatic, overly emotional, and susceptible to impressionability, with a tendency to consider relationships to be more intimate than they actually are.