I love the fact that when we first saw the sneak peek of this scene, we almost all jumped on the jealousy bandwagon.
I mean, one of the incorrect quotes I made that day became the most popular of all the ones I posted.
Of course, in retrospect, I see Crowley's expression as one of surprise, even amused surprise, as in, "Angel, you've been keeping things from me?" echoing Nina's phrase, "You're a dark horse, Mr. Fell."
First, he probably noticed right away that Aziraphale was uncomfortable, and second, unlike Nina, he knows him well enough to know that the situation is probably not what it seems.
What I also like about this scene is that Aziraphale takes the time to introduce Crowley. And to a stranger, the way he does it leaves no doubt that their relationship is special, both in what he says and in his whole demeanor (the tone of his voice, his immediately more relaxed expression, the way he looks at Crowley).
And I love Crowley's proud little smile when he addresses Nina.
And I'm probably extrapolating, but the way I feel with Crowley's smile is, "See, the naked guy friend doesn't have a name, but I do. I'm the most important person in his life."
We know why Aziraphale didn't dwell on the naked man friend's identity, but Crowley didn't.
I like the fact that since Crowley has sensed that something is wrong and pieced together the few elements he has, he moves closer to Aziraphale as if to create a more intimate or safe space for Aziraphale to express himself.
And even more, there's the way he asks his questions, the tone of his voice, there's no accusation. It gives such a feeling of protectiveness.
Once again, I'm sleep-deprived, so I'll leave you with my nocturnal ramblings...