Idk how R would look for a BPD/NPD couple. I don't know how a BPD would handle that. Maybe lots of anger, but desperation that the NPD not leave?
I think it is going to be different in every situation, but I can share a little of my own personal experience.
I was diagnosed with Borderline Personality Disorder at around age 20, which I refused to acknowledge or address. I was diagnosed with it again in 2016 (in my mid-40's), along with PTSD/Complex-PTSD, and persistent depressive disorder. I was also codependent at various points in my life. After doing extensive work on myself over the past 3 years, my psychiatrist has indicated that I no longer meet the criteria for Borderline Personality Disorder, however, I do still struggle with, and am actively addressing, my PTSD/Complex-PTSD and depression.
In my teens up to my mid-20's I had an on-again/off-again relationship with my now xH, who has Antisocial Personality Disorder with narcissistic features. He was abusive, controlling, and a serial cheater. I was not aware of, or familiar with, ASPD or NPD at the time.
My response to his cheating, up until the final betrayal was to rugsweep. I was absolutely terrified of his anger and abuse so I tended to keep my mouth shut. I internalized the pain I felt from being betrayed, and when the pain, self-loathing and sense of worthlessness got to be too much, I would self-harm or attempt suicide. I had been isolated from friends and family, had no money, was not allowed to work, and felt completely trapped. On the rare occasion that I had the courage and strength to leave, it wouldn't last long, because he would make promises to change, and use his abusive childhood to draw on my empathy, compassion, and codependent nature ("My love would heal him and he would change"
. Combine that with a fear of abandonment, and I stayed longer, and tolerated way more than what I should have.
During one of the times I left I did engage in a ONS with an ex-boyfriend, in hopes that he would rescue me, and give me a reason to not go back to my xH. Turns out he just wanted sex and not me (shocker!). Feeling even more worthless than before, I went back to my xH. I never disclosed the ONS to him.
My xH then ended up in prison for quite a period of time. I remained faithful throughout. After being told for years that I could not live, survive or even function without him, I realized through living on my own and supporting myself during that time, that I actually could - that I was stronger than I ever gave myself credit for. So when he was released and I discovered that he had been carrying on an EA while in jail, I was done.
If I look back at the dynamics now, I can see that the fear of abandonment and self-loathing from the BPD combined with the denial and control (believing my love could change him) of the CoD was a recipe for rugsweeping, and tolerating so much abuse and disrespect.
Would the dynamics have been different had there been no abuse involved? Quite likely. Had there not been overlapping of BPD and CoD would that have changed the dynamics again? Entirely possible. Would the dynamics have been different depending where on the spectrum each of our personality disorders feel? Where on the spectrum my CoD fell? I'm inclined to think yes.
There are just so many variables that can affect not just these types of relationships, but relationships in general, that we can't really make sweeping statements about them and paint them all with the same brush!