Couldn't agree more with empaths comments above.
Why questions, especially when asked about complicated relatioship dynamics... .are almost always met with a negative response. Not just with pwBPD. They are LOADED questions. WHY is what a litigator leads with in a courtroom... .it has the tendency to make people feel on trial.
Most of the stupid stuff we do in relationships ... .we do for unconscious, complex reasons that are not available to our immediate awareness... .for example, lack of intimacy/closeness when it use to be different, that happens in a lot of r/s's... .most folks actually don't REALLY know why that happens... .why they felt close or enjoyed intimacy with a person and now they don't... .?
and...
if a person actually has BPD... .they are even
LESS likely to have awareness of WHY they do what they do inside of a relationship... .so when asked WHY... .they feel scared and attacked and so they try to come up with plausible answers... .
the plausible answers almost ALWAYS move to an explanation that externalizes the reason... .meaning... .it's because of
YOU! So... .when you ask WHY... .you are inviting this person to speculate about why they do totally odd things inside of a r/s... .and they are going to point to YOU or something outside of themselves as the reason... .because that at least makes some sense and can be pointed to... .so that's where it will go.
And that sucks... .we don't like feeling blamed for everything, understandably.
My suggestion?
You could share how you feel about these things instead of asking
WHY this person is or isn't doing something. This has a different feel... .you are taking more ownership of your own feeling state.
"I notice I feel really sad, lonely etc... .when we are not as close as we use to be... ." you could also ask if they feel that way, too... .or how they feel about it, in general... .being curious, or exploring... .feels much different than asking WHY?
or you could query it in terms of a 'we' reflection... .instead of putting all the onus on your partner... .
"
I think we were happier as a couple when we were more intimate... .I would like to work together on improving our closeness as a couple again... ." etc.
This is not a quick fix in that the response will be perfectly delightful and thoughtful just b/c you avoid using the word 'why'... .but those
WHY questions almost guarantee a bad result... .so I think you will notice a difference if you stay away from it.
Some times we do just want to ask WHY WHY WHY?... .that may be more in the lines of needing to vent... .If you just need to vent... .come here... .or vent with a friend... .or with your therapist... .
There are many very accurate and insightful explanations that attachment theory and trauma studies can provide regarding WHY people behave this way in close relationships. Sometimes we have to read up on the science behind human behavior to get a grasp of our relationship dynamics. It certainly helps us to not take it so personally when we see symptoms that are common with many people, not just us. Most of the time, our partners are really the least equipped person to give us a satisfactory, insightful answer about why they do things.