I don’t have Borderline Personality Disorder (not to be confused with Bipolar Disorder - also commonly written “BPD”), but I’ve had a penpal who does for over 15 years.
I think many people see the words “Personality Disorder”, and assume it’s the same as “Psychopath”, but there are many different personality disorders. All of them cause problems with interpersonal relationships, but NOT all of them pose a threat to others, and often the individual worst affected is the person themselves - they are not violent, sadistic, or antisocial, although they may have thoughts of self-harm (but not harm of others).
BPD itself is a controversial diagnosis, with not all psychologists agreeing it even exists - although it’s in the American Diagnostic and Statistical Manual (DSM) - considered the practitioner’s bible! Some believe it’s just a position on a “normal” continuum, which we all find ourselves somewhere along. (Haha,started on this reply before seeing Doctor Geoff’s).
My friend does have a history of forming unstable and often unsuitable or abusive relationships, and does suffer badly from anxiety, and occasional thoughts of self-harm - which, to my knowledge, she’s never tried to put into practice, but she’s more upset by her inability to dismiss the intrusive thought she just might.
But she’s educated, interesting, and a conscientious worker. Just rather chaotic in her personal life.
BPD (or any PD) is not considered an illness, in the sense it’s how the person is, rather than something they’ve got. That’s why treatment options are rather limited and unsuccessful, as you cannot treat someone’s underlying personality (and something tells me it would be rather sinister if you could). It’s also the reason not everyone agrees with the medicalisation of it, because having a certain type of personality is not an illness. Are we in danger of medicalising anything that means: “Not like most people”, when it’s just the way some people are, and they’re not sick?