I'd be interested, too, to know which book is giving you such grief, waht.
I read quite a bit, fiction and non. Classics that I'm reading for the sake of "reading classics" I'll give a bit more leeway than current popular work simply because I'm reading it because I think I should. (Doing some background research into older, classic works helps a great deal. When you have the setting in history in which the book was written in hand and some context with regard to literary criticisms of the work, it generally goes a long way to giving you an appreciation for the work that you might not otherwise have. In other words, you know what you're looking at and looking for.)
Sometimes, I'm just not in the mood for a book, so I put it aside and come back another time. Sometimes it catches fire with me and sometimes not.
As far as popular fiction goes, the stuff that "everyone's reading" and you just "must read", if it doesn't grab me, I put it aside and leave it. There are too many other great authors whose work I know I enjoy, too much other really good stuff out there to waste my time forcing myself through something I'm not enjoying. It's got to be pretty bad, though, because I almost always finish books once I've started. However, there was one that springs to mind, The Life of Pi that won all sorts of awards, was a best seller for a long time, came with all sorts of rave reviews, and it just wasn't gelling with me. I got half-way through and moved on to something else. Sometimes, it just happens. And, yes, seerongo said, life's too short.