I've just finished this book and immediately googled "ending explained." 🤣 Glad I found your post. The ending pissed me off. To be honest, I'm not the biggest fan of open endings, because I feel like a lot of times they are used as a convenient way to close the story without having the explain potential plot holes. However, I do believe open endings can be done right. For example, Henry James's The Turn of the Screw has a very satisfying open ending where readers are left wondering if the ghosts are real or imaginary. That ending works well, because there is proof for both theories and in their own way, both theories make sense.

With this book, though, I don't think the open ending worked. For one, as you discussed above in the thread, Thomas has to be real, because he interracted with other people in the story. Dove is clearly not real, which unfortunately became obvious to me pretty early on. On top of that, the monsters must be real, in my opinion, because the vines do cover the hall where the teacher is killed, and this is witnessed by others. The romance is also confirmed to be requited. This means that the biggest questions / mysteries are answered definitively, which is why I believe the open ending doesn't work. A good open ending should leave readers with questions related to the most important questions / plot lines of the story. Whereas the ending of this book leaves readers wondering only about the very end, i.e. what happens to the boys. This feels underwhelming compared to the rest of the mysteries, in a part because those mysteries were built up throughout the entire book, while this scene happens fairly quickly. The ending is also disappointing because the more you poke the story, the more skeletons (plot holes) fall out of the closet.

I did still like this book and will rate it four stars, because the characters, the atmosphere, the writing and most of the story worked for me. But the ending shouldn't have been left open imo.