I don't think 'Suicidal A fails to sacrifice self for greater good; B notices' is a good representation of any of the tags it's trying to represent! Perhaps 'Character fails to sacrifice self for greater good & it turns out they wanted to die' is the better choice to represent this. In my view, the revelation after the fact that the character is suicidal seems important.

For the version unconnected with sacrificing themselves for the greater good, perhaps 'Character resigned to their death survives; doesn't know how to cope & other character comforts' would be a good compromise? I don't think 'A Expected to Die, Survives; B helps to comfort them' quite gets across the hopelessness and sense of being lost that the other tags for this scenario do.

There's a thought-provoking comment from an anon about this on the previous post, as well.