This is an awkward subject for both parties that no one wants to discuss. But from a blogger's perspective, I feel like it will benefit everyone for everyone to understand why scenarios like this happen.
To make things clear, this is truly an awful, awful thing to do. Nothing about this is right and no one should ever do this. If you received a book for free, you are obliged to review it. And if you really are not able to finish it, no matter what happens, you must leave a review.
Bloggers are always trying to stay afloat in a sea of ARCs
When an author's ARC request is accepted by a blogger, it might be ARC number over 100 (trust me, I know a lot of bloggers that actually have over 100 ARCs). Logically, bloggers should review those books in order, so that's why it takes so long. Sometimes, it's not just because the blogger is an incredibly slow reader, but it's because your book has to weight in line.
Bloggers tend to prioritize books with important due dates
Do not misunderstand this statement! This does not mean that bloggers in any way look down at you, or feel like your book is not good enough for them. What I meant is that bloggers often prioritize books on NetGalley, Edelweiss, or blog tours.
Your book was...not the best
This is one of those moments that made reading feel like a job, no matter how much we (as bloggers and reviewers love reading). All readers understand clearly that being forced to read a bad book is one of the cruelest forms of torture. If it's bad enough, reviewers might push it back, then, more back, then even more back, forever...
What should blogger do in this situation?
Review the book. Right now. It may be really, really awkward for both parties because depends on your situation, the book could have been given...ages ago. But don't fall victim to this mindset, and just review it. Once you have reviewed it, it's done. So keep thinking that way, and you'll clear out this problem in no time.
To all the authors out there:
You might be really mad, but you have to understand how busy the bloggers and reviewers can be. They have a life too, and they have their own priorities to get through as well. So I know this can be a really hard situation for you to cope with (and not blame and get really mad at the reviewers), so please understand.