I applaud Fanny for standing for her principles despite it being clearly impolite to contradict Henry in such a way. What effect did those words have on Henry? He did not repent anything he has done. He was surprised that she contradicted him, and then, after consideration, says "it was more pleasant then prudent", a conversational appeasement. The very next morning he declares to Mary his evil plan to make Fanny love him. So Fanny's opposition to Henry's words backfires spectacularly!