The central preoccupation of the show is that everybody is playing a role.

I love this observation, but I disagree, or at least would modify the comment to the extent that that each character's role-playing runs the spectrum from "nearly indistinguishable from actual personality" to "significantly removed from natural behavior".

Take Don/Dick. His role-playing is the most blatant, yet he's the most natural as well. He doesn't play Don, he is Don. In a way, he's so trapped by being Don, he can't even break character when he needs to - like when Betty is pleading with him to admit his affair. West-coast identity crisis ensues.

Pete (at least pre-airline crash Pete) doesn't even know who Pete is, much less, how Pete needs to behave. His role-playing is awkward and stilted - like he's in a play he doesn't understand, and he's forgotten his lines.

Joan is really good at her sex-bomb role, but this season she starts to see how limiting it really is. She hates it, but isn't ready to admit it.

Betty knows what her role should be, but unexcitedly goes through the motions, perfectly willing to phone it in if that takes the least amount of effort. Until Don's infidelity (tossed in her face by Jimmy) shocks her into reacting with actual energy - from kicking Don out, to finally going through with the infidelity she's been flirting with since the salesman from S1.

Sal plays half a role - himself at the office, and someone else at home. He's artistic, flamboyant and competent by day, and goes home every night to the lie that is his personal life.

I think Peggy plays her role with reluctance and some disdain. She's the most real in some ways. She makes no secret that she's not the biggest fan of church and sermons, but she doesn't hate religion either. She doesn't seem to hesitate or regret decisions like sleeping with Pete, or taking Freddy's office (well maybe a little regret on the latter). She dresses how she feels like, and changes her look because it helps her self-esteem and her career, but there's some reluctance there too.

Just a small note, but did anyone else remember that Pete got that gun by trading in the chip-and-dip they got as a wedding present? I saw it noted elsewhere.

One thing that hasn't been commented on, but I got a kick out of, was the 4 muskateers of creative traveling in a paranoid, bumbling pack throughout the episode.

Pete got that gun by trading in the chip-and-dip

I'd forgotten that! But that last shot of Pete, if it had been the chip-and-dip set? I would have been really worried that he was going to jump out the window.

remember that Pete got that gun by trading in the chip-and-dip they got as a wedding present

Continuity, o how I love thee.

It's an interesting question between identity and facade. Who am I versus who I present as? Self and avatar. What are my actual problems versus my perceived problems?

It's not actually Don's infidelity that tips Betty over the edge, is it? She'd known about his infidelity before. It's when his infidelity becomes apparent as public knowledge, as brutally revealed by Jimmy. Thus, when Don is not adequately keeping up his public role as husband and father.

That makes her more like Trudy than I'd thought until it was mentioned upthread. And Trudy is okay with Pete right now because where he strays from her planned role for him is not public yet.

The Don Draper Guide to Picking Up Women: [link]

It's when his infidelity becomes apparent as public knowledge, as brutally revealed by Jimmy.

Also, that even after that happened Don would not admit what he'd done. If he'd owned up to it right away I think things would have gone differently. And he still hasn't admitted it really. Just said that he didn't treat Betty as respectfully as he should have.

Was that Don not admitting it or was that the era's manner of talking about matters like that? We know that Jimmy was obnoxious and overly forward, so I don't think that it was odd that he said it, but perhaps you just didn't say that sort of thing in polite company.

We know that Jimmy was obnoxious and overly forward, so I don't think that it was odd that he said it, but perhaps you just didn't say that sort of thing in polite company.

Well, Betty asked Don straight out (or accused him I don't remember) if he'd slept with Bobbi and he could have been a man and said he did. I think it's telling that he didn't. And that she accepted his pale apology. It doesn't bode well for them.

and he could have been a man and said he did.

Well, but the kind of man Don is, is a complete fabrication. He lies every day in every way. Getting caught in a lie is not something he can admit to. That's why Betty was going nuts trying to find evidence.

Betty was also upset with who Don had an affair with. An older woman. A woman she perceived as vulgar.