Reached

Reached is the last book in a dystopian trilogy by Ally Condie. It was published in 2012. It takes place a few weeks after the first two books, "Matched" and "Crossed".
"Reached" finishes the story of Cassia Reyes in a five-part triple narrative split between Cassia, her boyfriend Ky Markham, and her best friend/match Xander Carrow.