Fan Casting Secret Relationship in Sort by Tropes

Two characters suddenly wind up in a relationship together and decide to keep it a secret from everyone. The reason can be perfectly solid, e.g. one of them is the other's boss, or one is a Secret-Keeper for the other, and making the relationship public would reveal too much, but just as often it can be an ill-defined "I'm not ready for them to know" excuse. They remain awkwardly but successfully concealed for several episodes, speaking in Unusual Euphemisms, constantly leaving to Talk About That Thing and generating many a "Fawlty Towers" Plot — basically put, behaving in such a manner that requires all other characters to juggle the Idiot Ball like crazy.