Pen Pal pt 1
there's a list of book club questions at the back of the novel that asks if you think the book had a happy ending and, i think it did. not in the most conventional way ever but aidan waited for kayla. that's why he didn't cross over. they may not get to be together in the physical plane but one could argue that they have an even happier ending because we know they can be physical in the spirit world and they can be together.