I abandon books all the time. Usually, I'll start reading it, realise it's not my cup of tea, but continue reading a few more pages/chapters, before becoming involved in the story, or putting it aside. Very rarely do I enjoy the story, and then get tired of it halfway through. Sometimes, I think books can start slow, but pick up well, and so I try to read quite a way into it, just in case.
One example is We Need to Talk About Kevin. The first four or so letters were very tiresome to get through, but I gave it a chance on the strength of all the recommendations I've heard, and it was worth it after that.