"The day you get your heart broken." Cristina takes a hammer to her ceiling fan to try and loosen it from her bedroom ceiling.
Derek and Meredith, meanwhile, are in front of a roaring fire, surrounded by wedding decorations, celebrating the "best non-wedding day ever." He asks if she wants to go again and she laughs, and then... well, you can figure that part out. "The day you meet your soulmate."
"The day you realize there's not enough time, because you want to live forever. Those are the biggest days. The perfect days. You know?" She's now wearing the scarf we saw earlier, and in the biggest non-surprise ever, she is saying all this to Denny, who tells her he bets she was a beautiful bride. She tells him it was a beautiful day, and then Alex walks in with champagne. He notices she put the scarf on when he told her she doesn't need it and looks beautiful without it. Next to him, Denny agrees. Alex goes to set the champagne down and Izzie says, "Go away now. Go away. I want to be alone with my husband." I don't know if he really didn't hear her, he's ignoring what she said, or he's just letting her settle things with her hallucination, but Alex doesn't react to that and just sits down on the bed, smiling at her. As he sits, Denny disappears behind him. He then pulls off her scarf to show her realistically grey bald head with an unrealistic lack of brain surgery scars, kisses her forehead and declares, "My wife is hot."
And with that, we look forward to the big two-hour season finale that only for the 87th or so time in 100 episodes, promises to be huge and shocking. Will Izzie live? Will she die? Or will they leave that as a cliffhanger until September or when news of actors' contracts shows up on the internet, whichever comes first? We'll find out Thursday!