A 26-year-old woman describes a new colleague as "the only person who has ever really understood her" within days of meeting them, then, after the colleague cancels a coffee catch-up due to a scheduling conflict, calls them "selfish and uncaring" and says she never wants to see them again. She describes a longstanding pattern like this across many relationships, alongside a persistent feeling of emptiness and an intense fear that people will eventually leave her. What is this presentation most consistent with?

This fits borderline personality disorder: intense, unstable relationships swinging between idealisation and rejection, chronic emptiness, and a marked fear of abandonment, as a longstanding pattern rather than a one-off event. It is not narcissistic personality disorder, where the underlying drive is more toward admiration for one's own superiority than toward desperate attachment and fear of loss. It is more than an ordinary falling-out, given how recurrent and extreme the pattern is, and how tied it is to fear of abandonment rather than a specific, proportionate grievance. And it is not histrionic personality disorder, where the central feature is dramatic, theatrical attention-seeking rather than this particular idealise-then-reject relationship pattern.