A 32-year-old woman presents to the psychiatry outpatient clinic with a 10-year history of unstable relationships, chronic feelings of emptiness, and intense fear of abandonment. She reports multiple episodes of self-harm (cutting) during times of perceived rejection, impulsive spending sprees, and a pattern of idealizing partners initially before devaluing them within weeks. She has made two suicide attempts in the past 3 years. On examination, she appears anxious and makes good eye contact. She becomes tearful when discussing her recent breakup. What is the most likely personality disorder diagnosis?