what is the most important and interesting conflict in the book?

In my opinion, one of the most important conflicts can be seen in Riley's determination to find and stay with Ever. Her love for Ever stops her from crossing the bridge with their parents, an act that leaves her somewhere incomplete and without her family. Her decision, in reality, leaves her with nothing. In the end, it is Ever, who loves her sister enough to enough to let her go, releasing her to join their parents... both girls facing the inner conflict of yet another separation, that in the end, will culminate in an important reunion.