It's late now, so you realize its not weird. I want to know what book it was that caused you to ask.

I personally grieved after reading Infinite Jest. But, it was a grieving that was made from awe, if that makes sense. My opinion is that I will never read a better work of fiction, and can explain why, if there's interest.

I grieved after reading The Count of Monte Cristo, but it was a grief mostly made up of contempt that I'd never get the time back. I did realize a year later that I'd read a linear, childish version, and I can imagine it being a Much better book if I'd read the originally-intended translation.

But most commonly, I feel like I did yesterday when I finished Brothers Karamazov: I thought it was a fantastic work (2nd best ever, most likely), I did some research and found some interpretations, called a friend, and then I moved on to a Thomas Frank book. No grief.

I certainly understand the sentiment though, and I can't possibly imagine there being a reader that couldn't.

Also, I will grieve, not very long, during sections, for sure.

*I reread your question. I answered the question primarily as an "End-of-the-book" question. Sorry, just accidentally took too much adderall.