I assume you are referring to Mrs. Osgood's party, which we are told Godfrey returns from at the beginning of Chapter 8. We need to remember that prior to this, Godfrey had given his good-for-nothing brother Dunstan his prized horse, Wildfire, to sell, to prevent his revealing Godfrey's marriage to their father. Therefore we are told that when he returned, he was not surprised that his brother had not yet returned, thinking that he will still be selling Wildfire and trying to get the best price. However, as the narrator goes on to reveal to us, he has other things on his mind that distract him from Dunstan and his attempted blackmail of Godfrey:
Godfrey's mind was too full of Nancy Lammeter's looks and behaviour, too full of the exasperation against himself and his lot, which the sight of her always produced in him to give much thought to Wildfire or to the probabilities of Dunstan's conduct.
Godfrey therefore is too busy thinking about Nancy, and his hopeless love for her, to be worried too much by Dunstan and what could happen.