Hi SadWifeofBPD
My understanding of this disorder is that some professionals consider this disorder to be related to PTSD. Some of us might be familiar with how adults have difficulty with PTSD. Now imagine a developing mind (toddler age 2-4) suffering a traumatic event from which they develop PTSD.
My understanding is that their "primary abandonment trauma" can be an actual loss, like the death of a parent. Or it can be a perceived loss (real or imagined). I suppose it can even be just a temporary loss. In some cases there might be abuse from a parent figure, or just the perception of abuse. Just like we don't understand why some adults suffer from PTSD, while others don't when experiencing similar events, I don't think we understand why some people might have a difficult childhood experience (abuse, loss, abandonment, etc... . ) and develop BPD, while others do not. The disposition of the individual should play a role... . some people may be more sensitive than others.
I keep reading that much of the BPD issue stems from something that happened to the person when they were about 2 years old. Some kind of abandonment, abuse, or something. Also, some kind of feelings of abandonment from the Mother. That is something that I wish I could explore more.
This is difficult to determine because the sufferer may be in strong denial of their trauma; I imagine this is especially the case in family abuse/incest situations. A good source of information might be the accounts of people who have recovered from BPD.
In the case of my BPD loved one, she told me about the loss of her mother when she was around 4 years of age. She describe to me a situation which I interpreted as her young mind being unable to tolerate or comprehend the loss of her mother that she completely dissociated from that loss. She only mentioned this one time to me in our five year relationship, and only during a very difficult period of her life (during the night she found out about another loss).
My pwBPD was a very difficult baby - a contrast to the first few easy babies in the family. His mom often speaks of how difficult this baby was and how she didn't want any more kids after this one. The mom was the type who likes to hold a quiet baby while she would sit and chat with the neighbors. This baby interferred with that. I suspect that he was often "abandoned" crying in a crib/playpen in a back room. (the Mom isn't one who bothers herself with unpleasant things).
Maybe it was the mother's invalidating behavior throughout this pwBPD's childhood development. Maybe there was a specific traumatic event. I don't know.
Even though the Mom didn't want more kids after this "bad baby", she found herself pregnant and gave birth to a super easy baby when the "bad baby" was 2 years old. I strongly suspect that Mom quickly dispensed with the "bad baby" because she now had a sweet baby to hold and tend to instead. The Dad worked from home and the family's pattern had been that Dad tended to the "older kids" once a new baby was born.  :)ad had a HORRIBLE temper and did NOT tolerate "kid noise". He was a scary figure, but the "easier kids" escaped much of his wrath. Bad Baby didn't escape his wrath. I suspect that when "bad baby" was abandoned by Mom to "mean Dad" that this furthered abandonment issues.
Am I off-track?
Your analysis sounds plausible. I hope your understanding can put it to rest for you. I also hope you realize that just because you understand what may be the underlying cause of your BPD loved one's disorder doesn't mean that they will accept or even consider your ideas.
Best wishes, Schwing