Why does Beatriz end her relationship with Nick in the novel, When We Left Cuba?

Unemployed, without school or a CIA assignment to keep her busy, Beatriz cooks for Nick and waits for him to come home, almost testing out the idea of being his wife for size. In testing out domesticity at the DC apartment, Beatriz realizes that it is not for her, and she is forced to end things with Nick, as she feels that she’s unfit to be a politician’s wife.