I found this very interesting. I think reciprocity is unbalanced with BPD ( from my own experience) and I think the "cause" is being in victim perspective with the over functioning person being in rescuer position. It's felt it's deserved. I also think it's a part of their identity and meets an emotional need of theirs. But to reciprocate goes against that need.
I too found it interesting, and it is definitely unbalanced with the BPD from my own experience with two different borderlines.
In the 'beginning' at least for the two romantic relationships I have experienced, there is love/sex bombing immediately from the first date on - so in a very distorted kind of way, they are making an 'investment' until you are hooked by making enormous love bank deposits, and when they perceive that you are 'hooked' then they will withdraw with entitlement that you 'owe me' for all of those deposits. It starts off lopsided, at the time, as I was too naive to know anything about BPD, I did try to match their energy of the love bomb, and then they stop, but they expect you to still maintain that matching energy they have become accustomed to. I'm a slow learner, and it took me way too much time to figure this out - decades. However, now that I have this figured it out, I can manage the transactional reciprocity of the 'push-pull' dynamic that my own individual therapist calls it.
Regarding 'meets an emotional need'. My personal observation is very similar to the parable that Forever Dad frequently shares of the endless pit, as I have felt that way in my acts of service to my wife. My theory is that the endless 'acts of service' is actually a circumstantial manifestation of the symptom "Persistent feelings of emptiness" where the pwBPD demands more and more attention (entitlement) in order to fill the insatiable emptiness that they are experiencing; however, no matter how much I tried, I could not satisfy her, and within couple therapy on many occasions, I have commented, quipped, that my pwBPD was "unsatisfiable".
It's odd to me but being in service to my BPD mother is an emotional need of hers- a large one. She seems to "need" people to be in service to her and in a way to be subservient to her. One doesn't "reciprocate" with their "servant".
I like the 'master - servant' analogy you implied, and sometimes it feels like a 'master - slave' as I have likened my acts of service to slavery to my wife, and I have called it 'servitude' in front of our couple's therapist, it wasn't received well by either by my wife or the therapist - so I have changed the way I speak on a full time basis and have changed it to 'lack of reciprocity', 'insufficient reciprocity', or something similar that is less triggering for her - yes, even though it is my most measures a 'success' my new way of talking to a normal person can still be perceived as 'walking on eggshells' as I have to modify the way I talk, so I do not trigger her.
She will even enlist people to do things for her that she doesn't need done for her- to meet this need. But ask her to do something for someone else results in being indignant. "how dare they ask me to do this". While her predominant behaviors are BPD, she also has a lot of NPD traits which may add to this.
Your describe you mom having comorbid NPD traits; whereas, my wife has comorbid OCPD baseline traits - so my wife does not manifest some of the traits in the same or similar manner as your mom in this aspect or in spending money unless her BPD is triggered, and then the BPD trait is limited to the episode which is temporary in nature induced by stress rather than the pervasive personality traits. My wife, with her excessive devotion and preoccupation with others she wants to keep in her life (favorite person) will do something for someone else with fierce rigidity and stubbornness striving to do something perfectly so it has to be her way.
This workaholism/perfectionist type attitude
previously interfered with our family life to the point of neglecting me and our children at disordered level described by the following four OCPD symptoms "Excessive devotion to work and productivity (not due to financial necessity), resulting in neglect of leisure activities and friends"; "Preoccupation with details, rules, schedules, organization, and lists"; "A striving to do something perfectly that interferes with completion of the task" all combined with "Rigidity and stubbornness".
She has also corrected nearly all of her OCPD symptoms as well using 'wise mind' or a variation of it.
I think a difference is if someone is self aware. It seems your wife is able to do that and in addition, if she is able to hold a job, she is also higher functioning. She knows what she needs to do to function in the workplace and that includes her behavior. So perhaps she is learning how to function better in her marriage.
My first individual therapist was joking with me that OCPD, when you read the symptoms of OCPD it is pretty much what an employer looks for in an employee. It is the most common PD, yet the least treated - why? Employers can take advantage of them as they follow rules and will do the extra mile and get the job done to near perfection - her OCPD is also what attracted me to her as well, as I personally value the non-disordered versions of these traits - I will start another thread on "BPD with OCPD comorbidity" on my observations and theories on this - as there are next to no articles on it, yet has a very high comorbidity depending on which NIH study is read (up to 50% for women and 42% for men). As a result her employers overlooked her occasional BPD fueled outbursts (snapping, yelling, and splitting on coworkers when they did not follow the rules and adhered to 'moral values') because she is incredibly smart, or issued 'warnings' on these behaviors.
Previously she also expected everyone she dealt with to be this way too, and if they weren't - this created stress and anxiety then the BPD portion would reveal itself.
But consider this- how is this happening? While you have focused on your wife's changes, I think the changes have been in response to your changes. We can not change another person but if we change our behaviors- they have the choice to adapt or not. You changed and your wife made a choice.
You are right we cannot change another person; however, we can ethically influence, persuade, and even manipulate the situation to induce change in a positive way - I did this under the supervision of a licensed supervisory level therapist.
You are absolutely right, I did change, in fact it has been a lot of change which will be a subject of a different thread as well as it is extensive. After the previous couple's therapist intimated I was changing, my wife responded a certain way, and by doing some mini-tests to see if she could 'adapt or not' - this emboldened me to 'call her bluffs', implement a series of fair, firm and enforceable boundaries - this is half of the changes that worked. The other half was changing the way I communicated which can be summarized as "stop arguing and start validating". Of course this is oversimplified, as I did a bunch of 'trial and error' to see what worked and what didn't.
It is possible that your wife won't respond intuitively to reciprocate if this isn't how she is designed but you can revert back to the transactional model if you find things are out of balance. Another way of looking at this is that, while it may feel transactional to you, it may be that you are developing better boundaries and are less inclined to tolerate the imbalance.
Initially she didn't intuitively reciprocate when I first started to push back on excessive acts of service - she attempted/gestured suicide - it took nearly two years of therapy to come to a point where it is no longer disordered; however, she is still pushing up against the boundary (at the urging of the couple's therapist) so I am doing some compromises here on the boundary, but maintaining the majority of it.
Thank you for taking the time to respond, it is greatly appreciated.