I think they are willing to put up with / indulge me reading something I enjoy to have a bit of close time together. The like the challenge of it being a massive book, but I remember finding the two towers pretty boring as a kid myself. I may stop for a bit after fellowship as I always thought that was the most readable of the books myself. I suppose that makes me not a true fan. I found the Silmarillion completely unreadable, but I do like middle earth.
Also recommended in this reply