Wiktionary
n. (context idiomatic English) A social scenario in which all participants are aware of a truth, but pretend to believe in some alternative version of events to avoid conflict or embarrassment.
Wikipedia
A polite fiction is a social scenario in which all participants are aware of a truth, but pretend to believe in some alternative version of events to avoid conflict or embarrassment. Polite fictions are closely related to euphemism, in which a word or phrase that might be impolite, disagreeable, or offensive is replaced by another word or phrase that both speaker and listener understand to have the same meaning. In scholarly usage, "polite fiction" can be traced to at least 1953.
An example would be of a man who goes out drinking, but tells his family that he is merely going for an evening walk to enjoy the night air. Even though everyone knows he will only be walking as far as the bar and will come home drunk, they all pretend that he really is going out for a walk, and pretend not to notice his drunkenness when he returns. Another common example is a couple that has had an argument, after which one of them absents him or herself from a subsequent social gathering, with the other claiming that he or she is "ill".
Polite fictions can slip into denial. This is especially the case when the fiction is actually meant to fool some observers, such as outsiders or children judged too young to be told the truth. The truth then becomes "the elephant in the room"; no matter how obvious it is, the people most affected pretend to others and to themselves that it is not so. This can be used to humorous effect in comedy, where a character will seem bent on making it impossible to maintain the polite fiction.
Usage examples of "polite fiction".
For the rest of the evening, Paul supposed, Kroner would be keeping alive - as with the milk toast now - the polite fiction of Shepherd's illness.
The polite fiction maintained by everyone else- that Earlene was a dull little housewife-was certainly more accurate, but it ignored a good portion of her life.
The profile fitshe's been in trouble since he was little, there are suspicious deaths all through the record, as well as what we know are a few actual murders, whether or not you buy into the polite fiction of temporary insanity.
The profile fits-he's been in trouble since he was little, there are suspicious deaths all through the record, as well as what we know are a few actual murders, whether or not you buy into the polite fiction of temporary insanity.