It may be God’s mercy that his suicide “failed”, because it might mean he had time to repent before he died.
Often people change their minds after they attempt suicide, which is often impulsive, and often due to drugs or alcohol.
And often a “failed” attempt is not trying to die, but a call for help.
As for “why”, one never can know. Depression is a terrible thing.
O the mind, mind has mountains; cliffs of fall / Frightful, sheer, no-man-fathomed. Hold them cheap / May who ne’er hung there.
Gerard Manley Hopkins quotes (British Jesuit Priest and Poet, 1844-1889)
fhu.com has the antidote to the evil that passes through our minds. Now used widely by our military! It works. Be Still exercise...free download.