A question of narration

For the past several years I have been particularly focused on the identity and influence of the narrator in fiction. Who tells the story? How is it told? How does what I know about the narrator affect how I read her narrative?  How has what I come to know about the story depend on what the narrator chooses or knows to tell? Or in the case of Huckleberry Finn, to what extent is the narrator capable of knowing.
     In Louise Erdrich’s new novel LaRose, a read I very much enjoyed, occurs this narrative passage: “Hey! Landreaux’s big face went wider and his soft smile came out. He shook Peter’s hand, whirling with apprehension, but maybe pleasure.”
     And I wondered: if my narrator cannot distinguish Landreaux’s emotion at this moment, then to what extent can I ever trust the narrator’s opinion about anything that the he/she says in the novel. How can a reader be assured of the accuracy of any assignment of feeling in the novel? There is an assuredness to the narration throughout this novel except in this once instance. The narrator seems certain that what she narrates has validity and accuracy. But without some confidence in what the narrator knows about Landreaux’s feeling here, then can I trust any statement concerning Landreaux’s emotions, or of the characterization of the emotional state of any of the character. And then . . . given this doubt, then to what extent is the entire story made (in)credible?
     There are significant novels with unreliable narrators, for example, Ford Madox Ford’s The Good Soldier. In Ford’s novel our narrator Dowell wonders “ . . . if one doesn’t know . . . at this pitch of civilization (at this hour and this day) to what have we attained . . . what does one know.” I admit here that Dowell even gets wrong as well the knowledge of “this hour and this day,” but he acknowledges “Perhaps you can make head or tail of it; it is beyond me.”  We have an identified narrator in The Good Soldier, and though he may be unreliable, may sometimes even remain blind to his own unreliability or be willfully ignorant of it, the reader knows the narrator is unreliable,
     But Erdrich’s narrator doesn’t offer to me in an any other place in the novel another suspicion of unreliability—and so this one moment intrigues me—does Erdrich herself not know Landreaux’s feelings? Has she at this moment stepped away from her narrator? And what does this say about the narrative of the entire novel?
     Of course, there is precedent for the author stepping into the novel and replacing the voice of the narrator—19^th century fiction is filled with such intrusions, but this instance in LaRose isn’t such an instant: this is the narrator admitting an ignorance about something the narrator has previously spoken of with authority: the character’s emotions. And so I am curious what effect this incursion has on my understanding of the novel! Better: I am interested to consider how I am to understand the novel given this narrative breakdown.