None of the characters in this story are very happy. The point of the novel is to illustrate that making people abide by moral rules that they don't really believe in isn't helpful in the development of their character. Instead of training people to behave according to the rules, what ends up happening is that characters like Nomi end up feeling disenfranchised, manipulated, and controlled.
Her life becomes about finding ways to feel autonomous, given the outlandish rules she must adhere to. Now, the rules might not be outlandish to a true Mennonite, but that's exactly the point of the novel—Nomi is not a Mennonite. Her parents barely believe the religious doctrine, and instead, they're using the Mennonite community as a quick way of teaching ethics and rules to Nomi, but the truth is that Nomi is losing her mind trying to figure out how to be a good person.
By the end of the novel, Nomi has learned valuable lessons. The right reason to not have sex with the wrong people isn't because God will hate you and send you to hell; it's because sex can be extremely destructive, and people are often untrustworthy. But Nomi must learn this for herself, the hard way, because she rejects the unwarranted rules and guidelines of her community.
