Persons who struggle with BPD will, by definition, have a weak, poorly developed, or absent sense of self. Our thread on
DIAGNOSIS: BPD. What is it? How can I tell? goes into that a little bit:
The Mayo Clinic
People with BPD often have an unstable sense of who they are. That is, their self-image or sense of self often rapidly changes. They typically view themselves as evil or bad, and sometimes they may feel as if they don't exist at all. This unstable self-image can lead to frequent changes in jobs, friendships, goals, values and gender identity.
Relationships are usually in turmoil. People with BPD often experience a love-hate relationship with others. They may idealize someone one moment and then abruptly and dramatically shift to fury and hate over perceived slights or even misunderstandings. This is because people with the disorder have difficulty accepting gray areas — things are either black or white. For instance, in the eyes of a person with BPD, someone is either good or evil. And that same person may be good one day and evil the next.
So it makes sense to me that if your friend does in fact have BPD, then she would behave differently and describe herself differently to different persons.
Is that working for you, in your friendship?
