Marry Me - John Updike

Sally is big, blonde and pampered. She’s married to Richard. But she loves Jerry. Jerry loves Sally in return, but he’s also still in love with his wife Ruth. Who’s been sleeping with Richard … As a hot, feverish summer of snatched weekends, secret phone calls and illicit lovemaking on the beach comes to a head, it turns out everyone knows more than they’ve been letting on. And that no one knows quite when to stop.