Never Let Me Go.

“I keep thinking about this river somewhere, with the water moving really fast. And these two people in the water, trying to hold onto each other, holding on as hard as they can, but in the end it's just too much. The current's too strong. They've got to let go, drift apart. That's how it is with us. It's a shame, Kath, because we've loved each other all our lives. But in the end, we can't stay together forever.”
― Kazuo Ishiguro, Never Let Me Go