You're so right about it being a stressful time. At my school, you're with the same small group (12 or less) of people throughout the 4 specialty rotations. That kind of intimacy is like a family. And as in any family, there's the good, the bad, the too-weird-to-describe, and occasionally the out-of-control. We've got variations of all of these in our group.
It's kinda funny that you posted this, because I've been noticing that a couple of people seem to be on the edge, and I would have thought it would be smooth sailing at this point. On the other hand, I know my own stress level is increasing daily as I undertake the ever-looming job search. I'm fortunate to be in an area with many hospitals, so I have choices. Maybe too many. I'm trying to weigh what's best for me & my family.
Maybe some of this is that we (most of us) have a healthy respect and maybe a little fear of the responsibilities we're about to take on.
As for the 2 buddies ... I'm sorry to hear it, but that's kinda (literally) a no-brainer. I can understand your conflicted feelings about it -- these nursing school friendships can feel intense, because they're based at least in part on the intense experiences you have in common. Their loss.
Hang in there ... eyes on the prize.