My partner has self-injured again after many years

[orangeagent]

I'm currently in a romantic relationship with a woman with BPD. She's diagnosed and is undergoing treatment since her teenage years. During the last few months, she's had highs and lows which I understand are typical of BPD.
From what I've read about other patients, she knows how to deal with BPD better than most people, and I've learned how to accompany her during the lows. But recently, she's been under a lot of stress, had a few fights with her friends, and injured herself. She told me right away, so I went to her house and she was feeling worse than any other time. We talked for many hours and she managed to calm down and see things clearly again. In that moment, she felt very ashamed and guilty about what happened. She told me she didn't harm herself since she was a teenager.
I want to know what could I do in future occasions like this, and how could I prevent it from happening again.

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