After an uninterrupted, prolonged period of unhappiness, a person may contemplate if not execute suicide. They hope to end their suffering. But does relief imagined to follow death occur? It seems only if one is alive and conscious can relief from sorrow be felt. In the meantime, the suicide has hurt countless others who care for them. One’s life has meaning if it benefits members of the species and, of course, the individual is a member of the species. Even if one has failed so far in achieving their prosocial goals, living is the only way to do it. And, there is likely no perceptible relief from pain via suicide.

I first attempted suicide back around 1992.
I didn’t really think about what to expect afterwards, all I wanted is for the pain, torment in my mind to quit.
I am not sure anyone really stops to think about what happens afterwards. You do know, or at least you do, but I reached a point I just didn’t care anymore.
Expecting relief due to death by any means, does not account for the idea that when dead there may be no capacity to sense relief. So, what’s the point of suicide? There is likely no ‘relief’ involved, just a hoped for killing of how one feels. I think without a feeling of relief, suicide is not really a solution to pain.
Yes, you are probably correct. Man may never know because dead is dead.