Audrey Niffenegger said this quote

Even her name seemed empty, as though it had detached itself from her and was floating untethered in his mind. How am I supposed to live without you? It was not a matter of the body; his body would carry on as usual. The problem was located in the word how: he would live, but without Elspeth the flavour, the manner, the method of living were lost to him. He would have to relearn solitude.