It seemed like the characters were dialectically wound together through a single story. On one plane you could almost say that maybe maggie was a young hazel and hazel was a older maggie. And the story revealed how their lives were a series of cycling moments of discovery, pain/hurt and reinvention as they go thru life having to lie, in order to protect them selves...
I too was hopeful that after they were found out, hazel and maggie planned to leave together but it just wasn't 'believable" . I liked an empowered iris a lot in the end though..