Edward and Bella are all dressed up for some special occasion. Edward has refused to tell Bella where he's taking her – it's a surprise.
Bella has a spaz attack when she realizes that Edward is taking her to prom. She's afraid to dance in public, but that's not the only thing that's bothering her:
I was mortified. First, because I'd missed the obvious. And also because the vague suspicions – expectations, really – that I'd been forming all day, as Alice tried to transform me into a beauty queen, were so far wide of the mark. My half-fearful hopes seemed very silly now. (Epilogue.28)
Once at the dance, Edward places Bella's feet on top of his, which makes dancing easy. She's actually having fun.
Then Jacob Black shows up, awkwardly cutting in and asking for a dance. He's ashamed that he has to deliver a message to Bella from his dad:
"Well – this is so stupid, I'm sorry, Bella – he wants you to break up with your boyfriend. He asked me to tell you 'please.'" He shook his head in disgust. […] "He said to tell you, no, to warn you, that – and this is his plural, not mine" – he lifted one hand from my waist and made little quotation marks in the air – "'We'll be watching.'" (Epilogue.103, 119)
Bella isn't too bothered by the message. She tells Jacob to let his father know she "know[s] he means well" (Epilogue.123).
Edward, clearly a little jealous, takes Bella outside. He admits to Bella why he brought her to the prom:
"I brought you to the prom […] because I don't want you to miss anything. I don't want my presence to take anything away from you, if I can help it. I want you to be human. I want your life to continue as it would have if I'd died in nineteen-eighteen like I should have." (Epilogue.157)
Now Edward asks a question: "I'm curious – what did you think I was dressing you up for?" (Epilogue.168)
[Bella:] "Well…I assumed it was some kind of…occasion. But I didn't think it would be some trite human thing…prom!" I scoffed.
"Human?" he asked flatly. He'd picked up on the key word. […]
"Okay," I confessed in a rush. "So I was hoping that you might have changed your mind…that you were going to change me, after all." (Epilogue.176-177, 179)
Edward has not changed his mind – he refuses to transform her into a vampire.
"Bella." His fingers lightly traced the shape of my lips. "I will stay with you – isn't that enough?"
I smiled under his fingertips. "Enough for now." (Epilogue.207-208)
The novel ends with Edward kissing Bella's throat with his icy lips.