To Proceed or Not To Proceed

I am about midway through The Post-Birthday World by Lionel Shriver. I found her previous novel, We Need to Talk about Kevin, fascinating; her newest book seemed similarly intriguing. The premise is a bit of a literary parlor trick: The protagonist, Irina, is in a long-term, comfortable, but unexciting relationship. Every year she and her husband dine with another couple, Jude and Ramsey, to celebrate Ramsey's birthday. One year, the year after the other couple have split up, she finds herself dining alone with Ramsey. And follows him home. And then... either kisses him or does not.

The novel then follows, meticulously, what happens after each decision. It's delicious wish fulfillment in some respects, a way to answer the question, "What would happen if I had only...?" The book is quite clever, and filled with pithy insights about fidelity and passion and compatibility. Yet I'm underwhelmed. None of the characters are especially likable; the prose, though intricate and brainy, seems to call a wee bit too much attention to itself and the writer's skill at writing impressive sentences; and the dual sets of chapters, each covering the same period of time, are kind of, well, tedious.

I do want to see how both narratives resolve, and I certainly have committed enough effort and time that abandoning the book is an unappealing prospect. Like I said, I'm half-way through. But I'm kind of bored with it, and other books are waiting in the wings (hint, hint). Should I plow through so that I do not squander the time I have invested thus far? Or decide that life is too short to finish a book I do not like? Unfortunately, I cannot see what happens with both scenarios simultaneously.

Do you give up on a book after deciding half-way through that you don't like it?