I think it may be difficult for those who've never been through a divorce, or a really bad breakup, to believe that there really can be "irreconcilable differences." Before I went through it myself, I'm not sure I believed it - if love really is all you need, shouldn't that make you able to reconcile and resolve any difference? Perhaps - the question then becomes what you're willing to give up to resolve it. Sometimes there are things we want, or don't want, or even parts of ourselves, that we'd have to let go of in order to preserve the relationship - and when it comes down to that choice, the relationship is what we have to let go instead.
People come together, and get married, with certain terms and understandings between them. If one person's stance on those terms changes, it alters the context of the relationship, and that's where Claudia and Ben are when he starts thinking he might want children after all. She's always known she didn't, and that becomes a difference that they can't reconcile. Meanwhile, nearly every other woman in Claudia's circle either has children or is trying to.
I enjoyed this book, although I found some of the plot twists a bit frustrating and others felt a little forced, and the resolution was a bit disappointing. The characters were well-developed and relatable, and while I didn't necessarily agree with all of Claudia's choices and actions, I could see her develop and grow over the course of the story, and I do like when that occurs. I like Emily Giffin's writing; I've read all (three) of her novels, and they have more depth and development than one usually associates with "chick lit." All of her books have given me things to think about concerning relationships; she doesn't draw in stark black and white, and I do find the grays more interesting.
I've pondered on this one a fair amount, but this book stirred it back up: In many stories, it seems that there's a lot more energy and anxiety expended over the prospect of having a baby than there is over raising a child, which is the true life-changer, if you ask me. I think it's not unlike the way there seems to be more put into preparing for a wedding than preparing for a marriage in many cases. Maybe both of these changes are just SO big you don't really grasp all of their ramifications until after they've happened, but I'd still like to know people are thinking about them more.