In twentieth century literature, the concept of waiting becomes a focal point. We see it in Fowles' The Magus, in Beckett's Waiting for Godot, in Pinter's The Dumb Waiter, and to a smaller extent in Sartre's The Age of Reason and Camus' The Plague.
We see a little of it in Marsh's "'Night, Mother":
"Mama: ...You wait.
Jessie: You do something else. You don't just wait.
Mama: Whatever else you find to do, you're just still mainly waiting. The waiting's the worst part of it."
You might recall this conversation later when Mama, frantic to stop Jessie's suicide, says:
"But something might happen. Something that could change everything. Who knows what it might be, but it might be worth waiting for!"
This reminds me explicitly of the last chapter of The Magus, where Fowles talks about the existential waiting for something to happen to you. And Jessie's response later reminds me of The Age of Reason, when Jessie refers to her lost self:
"Somebody I waited for and never came. And never will....I'm what was worth waiting for and I didn't make it."
But that's all I really have to say about this rather mediocre play. I have had an interest in the meaning of suicide in literature, but I'm not sure there was a great deal added to discussion of suicide in this play.