The Interestings by Meg Wolitzer

The book follows a group of friends who first meet at a summer camp called Spirit-of-the Woods designed for high school teens with promise in the arts--so a nerdy enough slice of people that you might continue to be friends well into the future.  The book covers the life of it's central characters from age fifteen until they are well into middle age.  They have relationships, careers, children, successes and failures along the way.

The cast of characters which numbers six in total includes Jules, who was an aspiring actress at 15 who switches to social work when her acting teacher asks her one day why she is bothering with lessons, that she has no passion or talent for the stage.  She has a friendship with Ethan, a talented cartoonist who has been imagining his animated alter ego since he was in diapers.  They veer towards romance but never quite achieve it and remain friends.  Jules has a brief affair with Josh, who later comes out, and Ethan goes on to have a love affair with Ash, who is also a great friend of Jules.  Ash's brother Goodman and his girlfriend Cathy round out the group.

The first fracture occurs when Cathy accuses Goodman of raping her one night long after they have broken up but they are out on a sort of date with each other anyway.  Goodman denies it, but then flees the country before the trial, and the group essentially ends up siding with Goodman, despite his potential guilt and Cathy is more or less out of the picture.  The remaining four are friends well into adulthood, with the book largely focusing on the inner life of Jules and how everyone else more or less relates to her.

The second tension is that Ethan makes it big, really big, and has more money than any of the rest of them can imagine.  It is the book version of 'Friends with Money' except that Ethan gets that no one can afford his lifestyle and bankrolls their relationship--with no strings attached and minimal hard feelings on the part of everyone else.  That is the first stretch of the imagination the book requires, but it is well written with a lot to say about what exactly friendship is and how to maintain it over a lifetime.