I don't think it's the "notice" part here. It's the "caring" part. To know that if something happens to you all your relatives and friends won't care or feel anything for losing you is the part that hurts, as for noticing. For sure they'll notice.
> One in nine didn't feel like they had anyone in their lives who they could rely on in a crisis.
It's entirely unsurprising that lonely people think other people won't notice if they're in a crisis -- that's what being lonely is.
There's a song called "How Do You Get That Lonely?", about a boy who committed suicide, in which the last lines of the chorus are:
How do you feel so empty
you want to let it all go
How do you get that lonely
and nobody know
The best option available would always be to meet a random person on the street because ending up with a bad person would not be as bad as dying.
I have friends (I know care about me) who simply can't have a serious conversation about hard or uncomfortable subjects. They wont engage... When everything is sunshine and rainbows this seems just fine, but when you're in tears over something, or feeling really bad, it's almost scary to see.