Various people have told my wife that they believe she is ill and needs help but she discounts it from them all.
Well, if she was told that she "needs help" in a condescending or invalidating way, I am not surprised at all that she didn't take it very well. PwBPD are
highly-sensitive people, and she probably saw these suggestions as persecution, rather than sincere, well-meaning advice.
why is it easier for her carry all the pain within her rather than get help?
I can tell you are quite frustrated (and rightfully so!) but I think you are possibly underestimating what the affect of carrying a lifetime of pain can have on someone's ability to even do seemingly-easy things such as admit to personal responsibility and begin therapy. In order to fully answer your question, we will need to consider what her early-life must have been like:
Did she grow up in an environment of emotional abuse, neglect or invalidation? Was she ever punished for getting angry or upset? Maybe she was made to feel wrong for even having feelings in the first place? This can lead to the development of Core Shame, as she may feel like she is flawed, and that there is something uniquely wrong with her. Also, were her emotional needs for intimacy met in childhood? Was she able to trust her primary caregivers to show her the affection she needed, or were they distant, absent or abusive? Has there ever been a situation in her life where she could trust someone with her feelings and it
didn't lead directly to more pain?
Now fast-forward through years and years of adult life. She is almost certainly aware of the fact that 99% of the people she's met don't feel emotion anywhere near as deeply as she does. Do you think this makes her feel normal or flawed? Do you think that she would expect
anybody to be able to understand her if she were to open up to them?
Considering all this, do you think she feels like she is even
able to "get help", or that maybe trusting a therapist with her feelings would just be a painful waste as nobody will be able to understand and help her anyway?
And yes, when you've gone your entire life carrying the pain inside it is
much easier to keep doing what you've learned to do your whole life, rather than trying to do something that is so hard for you it seems insurmountable and won't (in your mind) be able to work anyway.
what triggers a BPD sufferer to finally admit there's a problem and ask for help?
There's no easy answer here as most never get that far. My uBPD mom, for instance, is in her 70s and probably a lost cause at this point. Suicides are also common, unfortunately.
My dBPDxgf (who's been in-and-out of therapy since childhood and suicidal since middle school) got her dx in May as she was going through a particularly tough bout of suicidal ideation. Unfortunately, she's since dropped out of therapy again and refused to learn about BPD because she is "scared of learning about" herself. She also has an un-diagnosed dissociative disorder that complicates things immensely.
For me, I was a 20-year-old college drop-out with no career, no friends, no girlfriend, and no hope of getting any of those things. I literally could not believe my own lies anymore, and had to choose between finally accepting personal responsibility, or committing suicide. Even then, I refused to seek a therapist or let on to anyone how disturbed I truly was, and it was
many years later before I would eventually become more comfortable in telling people about it.
I think Once Removed is right. PwBPD will need to hit a similar "bottom" in order to accept personal responsibility and find true desire to change. Just going to see a therapist won't do it.