I can sort of understand the not trying to stop her any more. Sort of. Before my mother successfully killed herself (many years ago), she had tried so many times. She'd been considered mentally unstable enough to get a legal abortion in the early 60's, and had been hospitalized for "exhaustion" more than once.
By the time we reached our teens, her mental state was getting worse, and the attempts were more frequent. She refused all mental health care and self-medicated with alcohol and drugs that she diverted from my dad's medical practice.
You can't comprehend what it's like to live with that, unless you've experienced it. Every attempt at inviting a friend over requires carefully judging her mood. Every phone call when you're away from home puts your heart in your throat. You know that sooner or later, she's going to get the dosage right, or someone won't come by unexpectedly. Every day you live with the grinding misery that you can't help. You can't make them feel better, and either nothing else has made them feel better, or they've refused everything. You know that no matter how much you love them, and no matter how much you try, all they want to do is die.
And then, in my case, one day the phone rang. The dreadful anticipation was over.
You can't make someone want to live. Her parents had lived with years of seeing their beloved child want nothing but death. Nothing they tried had worked. They were at least lucky to be in a place where mental health care is decently covered instead of having annual and lifetime caps on what little care they allow. But none of it was enough to heal her.