I have suffered from depression (and still do sometimes) so believe me when I say: unless you're a trained professional, it's not your job to be her therapist.

I have suffered from depression (and still do sometimes) so believe me when I say: unless you're a trained professional, it's not your job to be her therapist. If she actively sabotages her therapy and her therapists can't figure that out, either her therapists are bad at their jobs or she's not yet in a place where she accepts that she needs help. For me it took a long time to acknowledge that it's not just my personality, it's a mental health issue and that there are people I could talk to about it (and that it needs to be an outsider). But most importantly I had to come to this realisation myself. You need to be willing to cooperate and to understand that this is a problem you want help solving. Sometimes the risk of losing the person you love is what it takes to make that step. But sometimes people need even more than that.