Less by Andrew Sean Greer

This somewhat surprising almost whimsical book won the Pullitzer Prize this year and so has become the "it" book.
 It introduces us to a minor novelist named Arthur Less (which is definitely a double entendre) as he finds himself abruptly single.  We first see him as he is coasting through a studiedly casual not-quite-relationship with a vain younger man for several years. Less is described as “an author too old to be fresh and too young to be rediscovered”, which gives you a bit of a sense of where this is all going. The younger man, who happens also to be the son of his arch enemy, then announces his engagement to someone else.
While still not acknowledging to himself that he was in love all along and that his heart is cracked, if not quite broken, Less accepts a slew of invitations that stem from his modest literary career, and conveniently fit together to provide a round-the-world trip. Not only will he thus avoid the wedding, but sidestep the pain of turning fifty in the company of people who know him.
The various stages of this journey lend the novel its structure and, as is customary, provide both a parade of colorful characters and a voyage of self-discovery.