I personally didn't like this much because there were just many things that were I think absurdly impossible. More than all that, if for example the two ex lovers were trying to have an honest feelings toward each other in order to either have a second chance or have a closure at their relationship then why can't the story be also honest with their respective partners. And besides after 15 long years, people do really change, it's just impossible to claim still that you know them all too well.
Anyways, here are my favorite lines from the book:
for all the planning in the world, one could not govern one's own fate
time teaches you what was actually important - and what was not
whatever happens, people find a way forward
every holiday has its hiccups
most things happen through a mixture of chance and human error
you have an idea of what I am.... but nothing more
we're a team, we'll always survive, you and I
I'm not unhappy, no. But neither is my life a piece of meringue you seem to think it is