The Post-Birthday World by Lionel Shriver

(Don't worry, there's going to be a February meetup also.)

Okay! At the end of March, we'll be discussing The Post-Birthday World by Lionel Shriver (whom, I had to look, is a woman). This novel about the decisions you make and how it affects the relationships around you landed atop Entertainment Weekly's Best Books of 2007. Here's more info from Publisher's Weekly via Amazon:

The smallest details of staid coupledom duel it out with a lusty alternate reality that begins when a woman passes up an opportunity to cheat on her longtime boyfriend in Shriver's latest (after the Orange Prize?winning We Need to Talk About Kevin). Irina McGovern, a children's book illustrator in London, lives in comfortable familiarity with husband-in-everything-but-marriage-certificate Lawrence Trainer, and every summer the two have dinner with their friend, the professional snooker player Ramsey Acton, to celebrate Ramsey's birthday. One year, following Ramsey's divorce and while terrorism specialist "think tank wonk" Lawrence is in Sarajevo on business, Irina and Ramsey have dinner, and after cocktails and a spot of hash, Irina is tempted to kiss Ramsey. From this near-smooch, Shriver leads readers on a two-pronged narrative: one consisting of what Irina imagines would have happened if she had given in to temptation, the other showing Irina staying with Lawrence while fantasizing about Ramsey. With Jamesian patience, Shriver explores snooker tournaments and terrorism conferences, passionate lovemaking and passionless sex, and teases out her themes of ambition, self-recrimination and longing. The result is an impressive if exhausting novel.

It's available in mass-market paperback towards the end of February, but your local library has it now and you've got two months to find it!