"Ah, Porphyro!" said she, "but even now Thy voice was at sweet tremble in mine ear, Made tuneable with every sweetest vow; And those sad eyes were spiritual and clear: How chang'd thou art! How pallid, chill, and drear! Give me that voice again, my Porphyro, Those looks immortal, those complainings dear! Oh leave me not in this eternal woe, For if thou diest, my Love, I know not where to go."
And, just like that, Madeline speaks for the first time in the poem.
Even though she's made out to still be sort of dreaming, Madeline's also described as being "spiritual and clear"—as opposed to Porphyro, who's down for the count this stanza.
It sounds like Madeline was indeed dreaming about Porphyro and that she is indeed awake here. She says that he's "changed" because she's looking at him in real life, where he's "pallid, chill, and drear," as opposed to whatever he was in her dream (probably fit and tan).
Keats pulls a switcheroo on us back in stanza 33—Porphyro had before been consistently associated with fire and heat until he sank down like "sculptured stone," and here again we see Porphyro described as being cold. He's so still and cold, in fact, that Madeline's worried that he's going to die. How did our passionate heart-of-fire boy become cold-dead-statue boy?
And what about Madeline, for that matter? Does she think she's awake?
She's afraid of being left in "this eternal woe"—the place where Porphyro is cold and silent—but that place is in fact the waking world, where Porphyro is "mortal." It sounds as though Madeline wants to escape back to her dream, where Porphyro was presumably a lot less chilly.