In chapter twelve, Harrison, the band, and the rest of the people at their table have their drinks spiked with GHB during the charity event. He is unaware that this has happened, so he has no idea that he’s under the influence when he decides to have sex with Maddy.
The book, therefore, broaches the topic of not only cheating but also the issue of consent. Unfortunately, as neither Harrison nor Maddy chose to take the drugs, neither could truly consent to have sex together while they were high.
Discussions of consent and sexual assault are had during some of the chapters following this.