I think people forget that a lot of the most famous quotes about dissatisfaction aren't always from dramatic novels. They're from characters who made very ordinary, very human mistakes. One that's always stuck with me is from John Steinbeck's 'East of Eden'. A character says, 'And now that you don't have to be perfect, you can be good.' It's not a scream of rage; it's this quiet, heavy sigh of resignation. It reflects that moment you realize your entire life path was built on trying to meet an impossible standard you set for yourself, and the dissatisfaction comes from all the years you wasted in that pursuit.
Another is from a play, actually. Arthur Miller's 'Death of a Salesman'. Willy Loman's whole being is a testament to dissatisfaction with his choices. He's constantly measuring his life against a warped idea of success. He says, 'After all the highways, and the trains, and the appointments, and the years, you end up worth more dead than alive.' That's the ultimate horror of a life spent on the wrong path—the cold calculation of your own worth, and finding it lacking. It's a dissatisfaction that's been simmering for decades, not a fleeting mood.
For a more modern, internal take, Sally Rooney's characters are full of it. From 'Normal People', Connell's reflection: 'He knew that he could have been different, that he had made certain choices, and those choices had consequences.' It's that academic, almost detached analysis of your own unhappiness, which somehow makes it sharper. You can't even blame fate; you have to sit with the fact that you, personally, chose this.