Last day of school please help ~100 points~

Read the excerpt from The Importance of Being Earnest. Jack. I fear there can be no possible doubt about the matter. This afternoon during my temporary absence in London on an important question of romance, he obtained admission to my house by means of the false pretense of being my brother. Under an assumed name he … stayed to tea, and devoured every single muffin. And what makes his conduct all the more heartless is, that he was perfectly well aware from the first that I have no brother, that I never had a brother, and that I don’t intend to have a brother, not even of any kind. I distinctly told him so myself yesterday afternoon. Lady Bracknell. Ahem! Mr. Worthing, after careful consideration I have decided entirely to overlook my nephew’s conduct to you. How does Lady Bracknell's refusal to accept that Algernon has behaved poorly advance the plot? It leads to Algernon admitting that he has lied to everyone. It causes Jack to restate his decision to refuse to allow Cecily to marry Algernon. It leads to Algernon withdrawing his marriage proposal. It causes Jack to reconsider his accusation against Algernon.