Okay, but picture this. The reunion happens. We see Dean hug Cas. The embrace lingers on a little bit more than is comfortable for the audience watching. Dean’s face is all angsty pain and relief and need. Then Dean steps back because he’s gotta let Sam have his turn, of course.
So Sam does. Sam hugs Cas, but the whole time that it happens, Cas’ eyes are open and he looks over Sam’s shoulder to Dean. Dean stares longingly back. When Sam and Cas separate, Dean assumes his position in the driver’s seat.
Dean spends the whole drive watching Cas in the rearview mirror. At every stoplight, they gaze at each other so intensely that at one point, Dean doesn’t notice that the light’s gone green again and Sam has to prompt him to go.
When they get to the bunker, they finally take their eyes off each other. They’re still reeling. They still can’t believe it.
They spend the next few days grazing fingers, and shoulders, and hands every time that they pass by, because they always make sure that they’re passing by each other just a little too close, just to have the excuse to touch each other again.