Life means as long as there is a desire to receive pleasure, or he enjoys what he receives, or enjoys giving to others. If he loses this force, he is considered dead.
Therefore, when a person is unconscious, it is considered that he fainted, meaning that he lost the will power to receive pleasure. When a person commits suicide, it means he has come to a state where he sees according to clear evidence that he can no longer receive pleasure, or because he is indebted to many people, who will afflict him, and these afflictions will annul the little pleasure he sees that he might still receive from this world.
For this reason, he will not go to the next world because he must exert in Torah and Mitzvot [commandments] and derive pleasure bringing contentment to his Maker. This pleasure is so great that it can revoke the most terrible afflictions in the world.
Accordingly, we were given Mitzvot that are regarded as “Be killed but do not transgress,” where he takes upon himself the suffering of devotion because he believes that by acting in devotion it will give Him contentment. Thus, one who commits suicide testifies about himself that he derives no delight or pleasure from observing Torah and Mitzvot in order to bestow contentment upon his Maker.