For Frankie, real life is a thing that is only permitted for others. So ready to just get started with her life, Frankie approaches adults as if she already were one, but there's something else driving her need to be perceived by others too—she's finally feeling the weight of her adult identity beginning, and the effect is that she desperately must know where she fits into the world. Frankie is having her first existential crisis, entering her adolescence, and just like Jarvis leaves his childhood home, Frankie leaves her childhood identity.
And how does Frankie do on her quest of coming of age? Well, for starters, when the unstable soldier tricks Frankie into being alone with him, and when he begins to act in a sexually predatory way, she attacks him fairly seriously and escapes—a sign of her experience no doubt, but also of her incomplete awareness, because after all, she barely escaped a terrifying encounter that she didn't see coming—a sign of her innocence. So one answer to the question of how far she has come might be that Frankie is mature for her age, and she is mature enough to deal with the harsh realities of her adolescence. She's ready for the real quest to begin, one might say.
This is certainly the implication at the end of the novel. John Henry passes away into death and Frankie must deal with this knowledge, and the loss of Berenice who also passes into a new stage of her life, and Frankie herself must deal with these changes and more, because she is moving away with her dad to find a new life somewhere else.
The ending of the story is the implication of another. Frankie is not done with her quest toward adulthood, but is through the prologue and on to the main season of change, adolescence itself.
