Dean would like to be more encouraging, but Sam and Ruby have been stuck in a time bomb since he died. While Dean wouldn't have expected this of Sam, it was only a matter of time before their time bomb went off. You can't sustain a long-distance relationship indefinitely, not even on earth.

Dean becomes immediately wary when Sam stops shaking his head. He tries to figure out what he said. Of course, by big gestures, he meant to have Jake make it rain rose petals or some equally romantic movie bullshit.

Dean's brow furrows as he listens to Sam. He can't disagree that Heaven should be peace. He also can't disagree that Sam has been restless and unsettled for a long time. He'd offered Sam various options like a job at the roadhouse or to help in tinkering with cars. None of it had brought Sam any kind of real calm. "Okay. So what are you thinking?"