"Present, n. That part of eternity dividing the domain of disappointment from the realm of hope."
The kiss blows open some twisted version of Pandora's box; no matter how hard Dean tries, he can't shove the thoughts back inside.
Distracted and pissed off at the world in general, he goes into their next hunt hoping to vent his frustrations. Naturally, the situation devolves until he and Sam wind up surrounded and unarmed, bordering on totally fucked.
Between one breath and the next, they're back at the motel, Gabriel complaining, "I can't leave you two alone for five minutes, can I?"
Dean finds himself wondering why Gabriel saved their asses, instead of the angel he prayed to.