This Book refers to American Girl performed by Tom Petty and the Heartbreakers
Amy writes about waiting for the pregnancy test results, noting that she turned on the radio to pass the time, and heard the Tom Petty song, 'American Girl' playing. (p.204)
Gone Girl takes up the story of Nick and Amy Dunne's difficult marriage, which is floundering for several reasons. Nick, a former journalist of some seriousness, loses his job due to downsizing. In a somewhat desperate state of mind, he relocates himself and his wife from New York City to the small Midwestern town of North Carthage, Missouri, where Nick is from. There, he opens a bar, using the last of his wife's trust fund, and runs it along with his twin sister Margo. The bar provides a decent living for the three Dunnes, but the Dunne marriage becomes more and more dysfunctional. Amy loved her life in New York and hates what she considers the soulless "McMansion" which she and Nick are now renting.