Just bought the physical version of "dont let the forest in" and I think I finally get the ending. So, its pretty obvious the monsters in the forest are a metaphor for the forest becoming something "dangerous" after Dove's death, or at least something they should avoid, but the whole "burying their hearts" thing is about how, to make the forest less threatening in their own eyes, they would have to accept that Dove's life had ended right there, in the forest. Dove is their hearts, and by burying them, they would be letting go of the idea she was still with them. Except Andrew didn't let go. Only Thomas buried his heart, symbolizing how he let go of Dove as well, but Andrew kept his, because he never truly believed Dove was dead, choosing to live in denial and self-deception instead. Thats probably really obvious but i'd seen someone say it was a metaphor for a double suicide and that just..... Didn't sit right w me. So maybe it's me who isn't willing to bury their own heart but i prefer to believe theyre alive and being eaten up by grief instead