I've no idea what happened in this instance, but one of the more common reasons for being sectioned (compulsarily hospitalised for mental health treatment) is if someone's known to be a high suicide risk and a serious danger to themselves. As I say, no way of knowing in this instance whether that applies, but it's one of the more common reasons for compulsarily hospitalisation.

The presence of an ambulance ready to take her to hospital, doctors assessing her under The Mental Health Act, and police backup, means they did come to potentially 'lock her up'. Though there's absolutely no shame in that.

I've known quite a few people who have suffered breakdowns of one sort or another, but I've never personally known of someone being assessed under The Mental Health Act, or indeed sectioned under it. It does sounds like quite a serious incident to me. I hope the papers don't hound her to pieces when she gets out, but it's impossible to imagine her getting any peace. It's a very sad situation.