Let us take this from another point of view: suppose one has suicided, we can not say that this act is the will of God, right? So, how to put all of those items in a common framework to understand exactly where is the will of God, and where is the law of (fallen) nature?
This is why, normally, suicide is such a serious sin.
Sin is destructive by its very nature. This is how it results in death which is the obvious decomposition of the creature.
But yet in Christ death has a remedial effect for instead of being simply destructive it becomes a humbling force against sin. Suicide however goes consciously against this possibility of a remedial relationship to death and instead accepts it for the brute destructive force that it is.
Where we see the will of God in this regard is where the destructiveness of death can be entered into by us as means of achieving life in Him. Note though that this goes not only for physical death but also for those many situations in life which call for a spiritual death to oneself- ie humility, patience, etc. This is why an ascetic life in Christ is a foreshadowing of our actual death or at least a training for it.
In Christ- Fr Raphael