And by "check on" I mean, "Talk to her until she relinquishes what little self-respect she has, because that's what Dan does best, and then sends her right back into Chuck's arms. For what reason? That she is disgusting and essentially unlovable. Basic Dan Humphrey stuff, we don't really need to go there. Except to note that by the end of the scene Dan and Blair's 'ice' is melting, there's a chilling moment in a while where he is acknowledged as part of the Waldorf-Rose family for no reason, and that can only mean they are going to hook up, and when that happens I shall be forced to go on a killing spree."
While Rufus tries desperately to find Lily, who is of course not at Canyon Ranch and has just completely stopped trying to cover her tracks, Blair runs to Chuck with the news: Dan has just informed her that she is too disgusting to be with anybody else. Fucking magnets: That's how they work. "We've both hit rock bottom, Chuck, but we've hit it together. At least we won't be lonely in hell." Chuck is not reassured by this nihilistic, essentially suicidal pronouncement, because it's not romantic to be told that you are the punishment and that being with you is the new bulimia, but she just peaces because -- on the other hand -- she is correct about this situation.
If you're wondering what went down with Eric and Elliott, Dan's on it. And the answer is nothing, because Elliott never showed up. There's a super long shot of them getting in a car, and then Rufus leaving pissy messages on Lily's voicemail, and then Cyrus --- while scrubbing the entire UES clean and crying about something that happened in middle school -- readies to ask Vanya some questions about Dorota, because it's another custom crudely sandwiched into being a parallel for the various lies and secrets and tests and whatever that are happening all over the place.
Nate orders Serena not to hang out with Carter anymore, because he makes her lie all the time for no reason, and she says that he has no right to do that, and he takes off because actually, yes he does. He doesn't get to dictate Serena's behavior, but he does get to choose whether or not he has to be in a relationship with a huge liar who goes around to randos' hotel rooms. Even Nate is like, "Why would your dad possibly be in Carter's hotel room at the St. Regis?" Whatever, you two. The whole UES is on notice this week, I don't have time for your shenanigans. Go eat something. In fact, I'm going to grab a beer and let this next part happen naturally: