I wanted there to be some sort of other understanding or plot twist but the truth is that this is a book trying to make an inappropriate sexual relationship between an adult and a child ok. I think I could have even been more understanding if Wavy had been older (age of consent) when she started fooling around with Kellen.
It’s a sad story full of terrible things that happened to Wavy and her brother and there is a lot of abuse and neglect that went unreported. That still doesn’t ever make it okay for an adult to molest a minor, even if they want it to happen.