Hello, I'd like to help you with your question.
There is no standard test for Borderline Personality disorder
unfortunately. Because the symptoms can vary so much and often overlap with other disorders, it is very difficult to diagnose someone with BPD. The three therapists that your husband has seen already should have been able to recognize the traits and diagnose him, but treating the BPD is another story.
Personality disorders are typically ingrained behaviors that someone develops, usually in response to being raised in a dysfunctional home. The person could not get their needs met (for unconditional love and attention) so they developed other ways to get what they needed which usually involved dysfunctional behaviors. When they grew up, they continued these behaviors even when they were no longer needed.
Treating someone with a personality disorder can be difficult. For one, they have to recognize they have a problem and be willing to get help. Also, personality disorders are hard to treat because they are ingrained in the personality of the person. So treating them is altering the person's perceptions and some basic personality traits. That does not mean they cannot be treated, but the effort it takes on the part of the person is more intense.
There are some on line tests that can be done to get an idea if your husband has BPD. Along with self help and information, you can determine if he may have BPD. Follow up with a therapist who has experience treating personality disorders is the best way to help your husband. Here are some resources to help:
I hope this has helped you,