It is upon each soul to recognize its limit.
Don't blame yourself, or worry. Neither does a bit of good.
Men live, and then they die. It is the quality of the process of living which matters, that and that alone.
The universe forgives those who give until their hearts are aching and their spirits weak, and finds a way to renew all strength and cure all ills, in this world or the next, if a soul can just have faith.
And as for death - we get what we expect.
Niko knew death like a sister - she was his true partner in the phenomenal world.