My husband has attended 2.5 years of individual therapy with a DBT-informed therapist and has completed 3 rounds of DBT. And this was after doing individual therapy with 2 other therapists (who were not that great), and couples counselling, and trying several different kinds of medication. His behaviours are not even nearly as severe as many other partners have described - mainly when triggered, he dissociates and yells to himself in a loud voice as if no one else is there. He also hates that he yells and says he does not want to do this anymore when calm (but still does).
Here's the thing - if the person experienced trauma, and I don't know if your wife did, but many people with BPD have very early attachment trauma, then in my experience, it is not enough to do DBT. That is a good start, but the person needs to work on processing the intense shame that is the hallmark of BPD and which is generally associated with the trauma they experienced. And that can be a very, very difficult, intense and painful process, which requires a high level of personal motivation to achieve. It cannot be "pushed upon" someone, they have to want very badly to work through their issues. I would not say my husband has "hit a wall", but I would say that it is just a long and challenging process - for some, it may require a lifetime of work to truly become healthy.
You can quote me all the studies in the world, but they are just academic words. I'm not trying to make you lose hope, and there is hope; however, BPD is not that easy to treat, contrary to what you may read. In the past, mental health professional thought it was untreatable, so I think it is great that there are actually therapies now that can work for motivated individuals. However, the authors of the study don't live with the person, and it is difficult to quantify things like what "no longer meeting criteria" actually looks like in real life. So I am not suggesting you give up, but just trying to keep it real - it's not like you do DBT, take medication and you're good to go.



