These folks all seemed to be not too upset by what was going on. There were all these happy little background stories. But they kept getting more and more grim. !!SPOILER ALERT!!
Describing the blond hair floating on the water, smashing up against the rocks. The shootings. The dogs! All these things contrasting against the unbridled optimism of the Guernseyites made it seem even more horrid. For me, anyway.
And the ending did seem a bit trite, all 'happily every after' and such. I learned, though, that Shaffer died before she could complete the rewrites her publisher had demanded. So that was taken on by Annie Barrows, a noted children's books author. That may have changed things a bit. I wish I could read Shaffer's original.
Now Grisham, he's written so many books that if you read enough of them you can pretty much predict the way it will end. Some people really like this one and thought it showed originality. And some people are calling it racist, sexist, and boring. So, YMMV. I would point out that both the Grisham and Shaffer books take place in the 40s.
Hope your day gets brighter.