Suddenly, Foible arrives in the dressing room and interrupts the exchange between Sir Rowland and Wishfort. She informs Wishfort that the dancers hired to entertain Rowland have arrived and one of them has a letter she must deliver to Wishfort herself. Wishfort excuses herself and exits.
More dramatic irony, in which Foible is dutifully delivering the very letter—Marwood’s anonymous letter—that is about to reveal that she and Waitwell and tricking Wishfort. Congreve is playing with the audience’s expectations.