Which disorder is most likely indicated in a patient experiencing intense mood swings and fear of abandonment in relationships?

The symptoms of intense mood swings and a fear of abandonment in relationships are hallmark features of borderline personality disorder (BPD). Individuals with BPD often experience rapid changes in their emotional state, moving from feelings of intense happiness to deep sadness or anger in a short period. Additionally, they have a pervasive fear of abandonment, leading to efforts to avoid real or perceived separation or rejection. This fear can manifest in clingy behaviors, impulsive actions, or even self-harm when faced with the possibility of being left alone.

In contrast, bipolar disorder typically involves mood swings that are more chronic and episodic, characterized by distinct manic or depressive episodes rather than the unstable interpersonal relationships seen in BPD. Major depressive disorder focuses on prolonged periods of low mood and does not intrinsically involve significant interpersonal fears or the rapid emotional shifts characteristic of BPD. Obsessive-compulsive disorder is characterized by intrusive thoughts and compulsive behaviors, which do not directly correlate with fears of abandonment or intense mood instability. Therefore, the combination of symptoms described strongly aligns with borderline personality disorder.