I don't see comfort anywhere in that scene -- I see confusion and longing, but not comfort.
The discomfort has a different source in each of them. Ennis's is based on his confused and ashamed
"I'm not queer!?! but I can't help but follow up on this anyway...!" reaction - Jack's comes from Ennis showing such strong reluctance to address what happened as well as such an (at best) ambiguous reaction to it all.
Whether one or more days passed, Ennis seems to continue struggling much in the same vein until he yields to Jack's kiss and caresses in the SNIT.
But something must still have happened inbetween IMO, because at the beginning of the SNIT *Jack* is more relaxed and more confident. He's giving Ennis the time he needs, but also seems to feel relatively sure about what will transpire. When Ennis approaches the tent, Jack seems to anticipate and even expect it - it's as if he was certain it would happen but thought Ennis might need a little more time.
All that could be based on Jack's interpretation of the "one shot thing we've got going" line - but I'd absolutely like to think it's based on something more, something that happens after Jack's "me neither" and before the film picks up again. They must have talked some, or have let their eyes meet directly to do the talking for them - exchanged unguarded glances - or even touched; - at any rate some understanding has formed and passed between them that makes for less uneasiness on Jack's part (and probably also on Ennis's) than in the mountain scene we get to see.
I think there's no narrative need in the film version for the time period between the FNIT and SNIT to be more than one day, - the journey Ennis makes is still the same, and with the same emotional impact. Whether fast or slow, the direction and destination are the same. (Yes, I do use Brokeisms in my writing, haven't I mentioned that?
) I do see what they were trying to do in the revised script though, where the understanding built more slowly and it took longer time for realization to hit.