One Day/ David Nicholls
Edit: An impulse buy, I didn't expect it to like it so much. Finished it in a day (today, aided by the fact that it was raining and, after a long break, I finally found myself back in a reading phase, which is good, because I have stacks to go through). The end was a punch in the gut, leaving a dull, lingering ache like how Atonement did. But it was necessary, I suppose. The way everything comes to an end.