A Spy in the House of Love
First off, whoever came up with the title for the ep is a freaking genius.
Andrew Chambliss' name might've been the one on the ep, but Joss most definitely had his hand in the final product, as his stylistic fingerprints are everywhere, from the plot of the episode to the way it was edited.
And in the dialogue - Chambliss has revealed that Joss wrote all of Adelle's lines.
That means that a significant chunk of the episode must have been written or rewritten by Joss. I wish I had known that when I first heard about Chambliss being chosen to write for Buffy season 9. Me and several other people got excited thinking "This guy wrote Spy in the House of Love, he must be really good". And then his writing for the comics turned out to be really unimpressive.
The 'A' and 'B' plot in the episode were connected through Adelle, due to the unresolved sexual tension between her and Dominic, which was hinted with her suppressed-emotion reply that she hasn't lost anything. She's heavily guarded with "real people" and she was only letting herself go and being vulnerable in the fantasy with a "person" who only exists when she allows it. Now she's even more sure she can't trust anyone.