Albert Camus puts it quite nicely near the beginning of The Myth of Sisyphus:
... Dying voluntarily implies that you have recognized, even instinctively, the ridiculous character of that habit [of living], the absence of any profound reason for living, the insane character of that daily agitation, and the uselessness of suffering.
...What, then, is that incalculable feeling that deprives the mind of the sleep necessary to life? A world that can be explained even with bad reasons is a familiar world. But, on the other hand, in a universe suddenly divested of illusions and lights, man feels an alien, a stranger. His exile is without remedy since he is deprived of the memory of a lost home or the hope of a promised land. This divorce between man and his life, the actor and his setting, is properly the feeling of absurdity. All healthy men having thought of their own suicide, it can be seen, without further explanation, that there is a direct connection between this feeling and the longing for death.
Rock on, Albert: "This divorce between man and his life, the actor and his setting..." Exactly. Exactly that.