Serena, high on the feeling of power that only a well-solved murder mystery can give you, re-explains the whole stupid thing again about the ring and how he wouldn't let go of the ring. The only person who A) Could possibly know this story and B) Has any emotional stake whatsoever in telling this story, not to mention it being a pretty great idea for a scene with Blair, is Chuck, but he's not around and Serena's jumping the gun. Blair wishes Lily all the best in operating the Empire, and hopes that she can manage it without becoming a whoremaster like its last owner.
"Blair, he's changing his name. His landlady said he's on his way to the train station." Serena says both of these things as though she is talking about a chronic illness, and B just laughs at her. "You fuckin' do it," she says, and tries once again to go have her fairytale, but S is convinced that only B can talk him into... Whatever it is Serena wants him to do. Stay Chuck and not vanish to India, I guess. Blair tries to get the fuck on up out of there so she can do the Givenchy thing, and Serena fully starts over again from the beginning: "Blair. Blair, he almost died holding onto that ring!" And, it's implied but not necessary to state, the hope of one day regaining Blair. But since it would only be totally cheesy and stupid to say it out loud, Serena does. "And to the hope of you!"
Blair, realizing that we're all in some kind of Nate Archibald brain-loop where you have to tell the entire story over and over again a million times before anybody gets it, reviews the facts for Serena. Chuck sold her literal ass to his own uncle, for money. She forgave him. Then Chuck had sex with Jenny and lied to her face about it while Jenny was still in bed in the next room, which anybody would say is a dealbreaker. Serena's like, "Okay. But you don't need to forgive him. You don't even need to talk to him again after today. But I know you, and you will always regret it if you do nothing and just let him disappear."
("Murder is never perfect," Serena thinks to herself. "It always comes apart sooner or later. When two people are involved, it's usually sooner. Now we know the Dietrichson dame is in it, and somebody else. Pretty soon, we'll know who that somebody else is. He'll show. He's got to show. Sometime, somewhere, they've got to meet. Their emotions are all kicked up. Whether it's love or hate, it doesn't matter. They can't keep away from each other.")