no treatment, no relationship
Well, that is surely one way to set a Boundary. That is,
your boundary. Read the boundary topics here on our
Tools and Skills board here. In other words, you can't force a pwBPD to behave differently, but you can set a boundary
on yourself ("I will leave") if you are to continue the relationship.
That said, that idea reminds me of the old saying, You can lead a horse to water but you can't make it drink. So your spouse attends therapy. What if the behaviors don't improve? You can't fix her, likely also because you're in the closest of relationships. BPD is most evident in closer relationships. She would have to want to recover
for herself (and to a lesser extent for others too) and stick with it for life, that's a very hard task to accomplish.