When a viewer, reader, or player finds the fiction they are perusing to be otherwise fine, but can't... quite... finish... The reasons vary: maybe it has Pacing Problems after the first half or the first main villain in the Sorting Algorithm of Evil is defeated, or it's become deathly dull post-climax, or the effort needed to beat the Final Boss just doesn't seem worth it, or perhaps the author just didn't know how to end it, couldn't decide on an ending and just threw all of them in. In the end, there is no end. At least for the reader, who has decided it's not worth the minuscule effort needed to get to the end and that final "cathartic payoff."