Caticorn, it is a hard road to walk. Deciding what is dysregulation and what is not used to drive me crazy until I realized that the very hallmark of borderline is precisely fuzzy boundaries. The wisdom to know the difference is what I pray for daily.
I say this because I have two behaviour patterns depending on what it is. When beloved dysregulates I disconnect emotionally, tell myself it is not about me, it is just an emotional storm that will pass. And try to listen to the deeper message because she has no choice but to try and communicate through the storm. So learning to "speak BPD" becomes my mission in those circumstances.
When she is at baseline I try to find out what the trigger was and how we go about defusing it. With time that approach is slowly helping us get a handle on reducing harm.
Coming back from dysregulation as a couple is always the hard part, I mean we are together because we want to be happy together and so the question of a path back from those emotional storms becomes a task in itself. If I have managed to identify it as a dysregulation and kept myself emotionally safe it is easier, sometimes compassion springs spontaneously and all I have to say is "how can I help you recover?" for there to be peace.
So I am happy that I am making progress in identifying the right questions, even if I don't have the all the answers.
I feel though that in a way you possess a superpower that many of us on these boards would give our left eyeteeth to have. To bring somebody out of dysregulation would be the key to happiness for most of us

Including our partners, because if it is hard for us to experience it from the outside it must be so much harder for them. If touch and sex works for your husband then I think it is altogether a miraculous thing.
I totally understand that sex must be consensual and pleasurable, and maybe you need to talk more about how it feels for you?
For us, when beloved allows me to touch her I can bring her down by rubbing her feet. I suspect that it is the feeling of being grounded, having someone hold your space for you and you to it, that does the trick. We can head off dysregulation if we spot it early enough by long hot baths and massages, and again it seems like you and your husband are onto something there.
Harri, I hear you about validation and agree that it is probably better as prevention than cure. I try to be mindful to pay her extra attention before dysregulation occurs, something as simple as making her a cup of tea or stroking her cheek as I pass can help when life imposes its extra stressors. And boundaries, communication around boundaries, are so important, our own tolerance has its limits and PTSD for partners of pwBPD is real. So not to stretch too far beyond our capacity - for me when I feel the urge to be violent back I know I have pushed my tolerance too far.
I think this is a great thread! And hope that others will weigh in. What works and doesn't work for people to bring their loved ones out of dysregulation and/or return to baseline smoothly?

Khib