I feel like the real issue for someone with BPD is processing incoming messages (verbal/actions etc.). When you're starting position is defensive and highly emotional, it's hard to be rational.... hence why messages are often misinterpreted and why people w/ BPD appear to live in another reality...they need to learn to slow down and use their rational brain to keep their emotions in check... I'm not sure she'll learn this from couples therapy
You might find this book helpful:
The Chimp Paradox: The Mind Management Program to Help You Achieve Success, Confidence, and Happiness
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