In “The Midnight Library” by Matt Haig a 35 year old woman decides to end her life. In her opinion that life has been a series of bad decisions. And nobody needs her anyways. So there is no reason to keep going on.
But instead of just dying after taking some tablets, she awakes in the Midnight Library where she can try out all those lives she might have had, had she made some other decisions.
It’s a deeply philosophical book ending with a predictable conclusion. But the way to that conclusion is a nice story worth reading.