One example of dramatic irony in this section of the text is when Montag returns home from his visit with Faber and Millie's friends burst into his house with their vapid conversation. Montag casually asks them about their missing husbands and whether they are fighting in the war, and one woman replies:
I'm not worried. I'll let Pete do all the worrying. I'll let old Pete do all the worrying. Not me. I'm not worried.
What Montag and the reader have come to understand is that most human relationships in this society are shallow and are missing any real form of human connection. These comments show the dramatic irony; Pete's wife likely considers herself concerned about him in some way but is too shallow to even realize that her superficial feelings about her husband are not borne in actual concern.
On the other hand, a further instance of dramatic irony occurs when Montag believes it possible to somehow connect with this group of superficial women through literature. The reader knows that the only possible outcome of choosing a poem to share with Millie and her friends will be disastrous. They have no depth, no desire for intellectual stimulation, and are more than content to engage in meaningless conversations about entertainment.
So when Montag begins the reading of "The Sea of Faith," the audience knows that this is a tipping point in Montag's life, yet he seems unaware of this, as evidenced by his final line in this section when Beatty confronts him about his choices: "Why, we've stopped in front of my house." The dramatic irony here is that Montag seems unaware that Millie would turn on him, although the reader realizes that Millie is incapable of depth or of leaving her "family" for something of greater substance.