Personally, I think all humans are sensitive to rejection, just by our very nature of being a social species. We need one another to survive, so we have always created "community" as far back as archeologists have tracked us.

So when you are rejected, it touches a very basic, innate response in our minds. Somewhere a while back (sorry, I can't remember the link), I read a study that showed that the mind's response to percieved rejection or ostracism is precisely the same as how it percieves physical trauma and pain. So in other words, the same part of the brain that processes physical pain also processes social rejection.

The reason for this is purely based in our survival instincts. Rejection literally causes your body to release a whole slew of hormones, including cortisol and progesterone, in order to essentially influence our behavior to be 're-accepted' by those who rejected us (another study altogether, again, no source, but if you really want me to hunt it back down, I can try). This study interestingly showed that people who had not experienced extreme traumatic rejection earlier in life responded with higher progesterone, which increased their amenability and desire to reconcile with those whom had turned on them. In the cases where the victim of rejection had experienced traumatic rejection in the past, their P levels actually dropped. Progesterone generally is a soothing, sedating hormone, thus leaving these victims in an extraordinary state of trauma, and often causing them to be more sensitive and withdrawn.

So I guess what I'm getting at is that is this... it could be, and probably is from both, but it is also a very natural response to a very traumatic experience for all human beings. So please try not to stress over it too much, okay? The more you stress, the more your poor body and heart suffers from it.

As for the bit about being very manipulative, it is my understanding that BPD's are often percieved that way by others. But here's the thing (and this is just my opinion, no research here), you cannot control how others see you, even a therapist. You can only control how you see yourself, how you react to others and so on.

It strikes me that you are researching and trying to understand borderline PD, which tells me that you want to be better. That fact alone is worth self-reflection. Are you manipulative? Or are you being seen as manipulative by others. There is a big difference. In my opinion, this is where you start self-growth: when you start to be able to see yourself with clarity and learn to control your reactions to others, whoever they may be and however they may treat you.

Briefly, I only say all this because I recently suffered a traumatic rejection from one entire side of my family and they called me a lot of nasty things. So I started reading and learning about why and how I could feel that way and be seen that way. I've come a long way since that painful rejection, but I just want you to know that I know just how much a rejection can turn your life upside down and your heart inside out.