Many people have commented that we tend to get a lighter episode before the angst-fest starts, but I think there was some more specific foreshadowing of events to come in this week's episode.
Remember this season's mission - to take everything away from Sam and Dean - and then look at the two things that were important to the boys this episode.
"If it bleeds you can kill it"
Dean's advice to Sam is actually a quote from "Predator", and as far as advice in the SPN world goes, not really practical - lots of things they face can't bleed. And that's the point - its not the content of the advice that helps Sam, it’s the fact that it's from Dean. He repeats it again and again like a, clinging to it like a talisman.
Just Dean's words are enough for Sam to beat his fears.
Dean is the one who helped Sam tell reality from his Lucifer occupied psychosis and he literally is I think what Sam has made his rock. Dean is his constant. It's the loss of Dean that he's afraid of - "we're okay aren't we?" And yes, the revelation about Amy has him storming off - but I think as much because well - if he can't trust Dean what can he?
And I note at the end of the next episode, when they reunite, a lot of people commented that when Dean says"And as far as how I been acting... I don't know. Maybe it's 'cause I don't like lying to you. You know, it doesn't feel right. So, yeah, you got me there. I been climbing the walls.", he's lying to make Sam feel okay. And I think he is.
But I also think when Sam says "Look, you know what? Um... You were right. About Amy. If she was... just any monster, I'm not sure I could have let her walk away." - he's doing exactly the same thing, so he can end the rift with Dean and they can reunite. That’s not to say I think his statement is wholly untrue, neither is Dean's, but being together is more important to both of them at the moment.
"You look like you got attacked by some PCP crazed strippers."
And Dean? He was in a rather bleak place at the end of the last episode. And this episode, Dean doesn't drink. He does the job. He teases Sam. He laughs.
Dean LAUGHS.
Sam is safe, and he looks ridiculous, and Lucifer isn't hanging around, and for a moment Dean is FINE.
And they exchange of presents at the end. We know this is unusual, these boys who'll die for each other aren't the gift giving type, and both of them put on some bluster that is a note perfect replica of how they sounded in A Very Supernatural Christmas. And then too the gift giving was in the face of them losing each other. It's in their sibling subtext. (those with Wincest goggles on can also note this was the Valentine's Day episode).
Dean is Sam's rock. Sam, Sam when Dean can believe he is okay, Sam is Dean's anchor, his constant.
So just what do you think each of them is due to lose next?