pursuingJoy 
Potentially lighter topic: I'm curious to know if anyone observes patterns of worship/discard in your pwBPD's pets? [...] What do you see?
I think the BP worships the idea of being in a relationship. It can be tremendously validating for a person's sense of worth—
vitally so for a BP's incapacitated self.
I see a similar situation for how the given BP 'worships' the idea of being needed by a pet. To me, the dynamic of need and provide is a close fit for a child and a pet. Both need you to survive. This need for worth being met by the actions of replaying dynamics with a child—it's well illustrated by some of the BPDM variants by Lawson (Skip's summary
here).
Under another lens, the
child worships the parent by their pairwise role as care-needer. Therefore, we can immediately see the potential use of the child as a source of validation is monolithic (from the act of giving parent-worship). So then we now see the BP gaining a massive supply of validation, and their "cultivation/building of the relationship with a pet"
seems to us their effort to "worship" the supply. Simply, the BP appears to worship the pet because they get a supply of something their self is often craving: validation.
With a pet, the BP gets to play this game of being needed for 15 years +/-, because a pet can't go out and be self-sufficient. Of course, you can tack on ideas that pets can't be assertive like humans—so they'll never learn to combat the BP on civilised terms; and this list can go on. This is similar to
White Feather's idea that dogs don't require interpersonal skills to give their owners comfort.
From the spouse/partner perspective—my UexpwBPDgf wanted 2 young dogs. They were at 3 months each. Both strays from the shelter. I told her I wanted 50% effort from each of us—basis was that we were both working adults. According to my calendar, I did about 98% of all the work on both of them.
I think it's a good example of how both of us treated our relationship.
She wants to enjoy the relationship's benefits—but her deficient capacities caused her to shirk her responsibilities. I wanted 50% contribution from her, she gave 2%.
I want to enjoy the relationship's benefits—and I was willing to tolerate doing the extra 48% of her share. I wanted 50% contribution from me, I gave 98%.
I learned that it can be painful to look at the proportions we put in. I learned that we don't pay attention while we are working at X task because the present realities benefit from
the non having the ability to function at whatever point in time—i.e., I can't have an anxious episode about how crumby my situation is while my dogs need me to be stable and calm so they don't give the vet (and I) a hard time at the clinic. I learned that being exhausted keeps us stuck repeating patterns that aren't good for us.
Regarding mindfulness, I learned that stepping back requires presence and calmness of mind—i.e., an environment that fosters self compassion. Imagine perhaps a quiet place by the lake. But in the enmeshed relationship of being with a pwBPD, imagine being immersed in the lake, the currents are strong, and you're treading water—tough to get presence and calmness of mind.
Regarding our own motives—part of what I learned was I didn't care about my self enough, and I expected some kind of reward value of being in a relationship with someone I perceived as societally attractive. I couldn't see how that was fair on me or my planned children being in these relationships with a BP when I had a
good great chance at getting out.
On the PSI board here—how this would help me is to understand the spouse of the BP, and I'd also add that if the spouse-figure did things that you didn't like, accept it as such and don't jump to finding excuses for them (as the child-figure). Look at what each of them did with a clean set of objective eyes and do what you need to do.
Enjoy your weekend.
