Hi angry observer,

She's had a very long term r/s with her bf, maybe they're having problems in the r/s, being thrown out for someone else brings things out in the open for others to see, she might feel embarrassed about what happened. A r/s is a very personal thing between two people, even if it's a r/s that you don't agree with, it's a good idea for friends and family to stay on the side lines and be supportive and not judge or invalidate friends that are going through this. I'm not suggesting that you're being judgemental or invalidating, I'm just saying that in general terms for anyone that is going through this.
I'd feel angry if a loved one was going through this, you can your feelings about it too, it's also a good idea to have those feelings validated, to answer you question if she might hurt her, that's a tough question because I can't predict the future, you could print the article in my post that helps members if a loved one with BPD threatens suicide and give it to your friend, but it depends on how receptive that she is, it sounds like they're going through a tough time and it can be hard to talk about those things for some people.
Suicide ideation in others