Wish You Were Here by Jodi Picoult

Diana O’Toole is perfectly on track. She will be married by thirty, done having kids by thirty-five, and move out to the New York City suburbs, all while climbing the professional ladder in the cutthroat art auction world. She’s not engaged just yet, but she knows her boyfriend, Finn, a surgical resident, is about to propose on their romantic getaway to the Galápagos—days before her thirtieth birthday. Right on time.

But then a virus that felt worlds away has appeared in the city, and on the eve of their departure, Finn breaks the news: It’s all hands on deck at the hospital. He has to stay behind. You should still go, he assures her, since it would be a shame for all of their nonrefundable trip to go to waste. And so, reluctantly, she goes.