[flashback to Lily and Marshall talking to Robin at MacLaren's:]
Robin: God, what am I going to do?
Lily: I don't know. What are you going to do?
Robin: I'm going to marry Barney in a big church wedding. We're going to move to some sleepy New Hampshire town and open a bed-and-breakfast.
Marshall: Aw, really?
Robin: No! It's Barney. I mean... it's Barney. But it's Barney. I got to tell him no.
Lily: Oh, man, you're going to break his... Whatever it is that pumps that black sludge through his veins.
Robin: Crap. You're right. The first time Barney expresses feelings for a girl and she rejects him? And not just any girl. I mean... It will destroy him.