McCain aides confront Cindy McCain over reports that she had an extramarital affair (page 281):
"The man was said to be her long-term boyfriend; the pair had been sighted all over town in the last few years. Members of McCain's senior staff discussed the unsettling news, and their growing concerns that Cindy's behavior had been increasingly erratic of late. [John] Weaver and others suspected that the Cindy rumor was rooted in truth. It was upsetting, Weaver believed, but not a threat."
https://www.theatlantic.com/politics/archive/2010/01/game-change-even-more-juicy-stuff/33234/
http://www.phoenixnewtimes.com/news/john-mccains-top-aide-believed-cindy-mccain-affair-rumors-book-claims-6638490