At this point in the series, is it really any surprize that people start to crack up? I'm glad the writers took the time to deal with that reality.
If I were in a similar situation, I'd behave as Dee (suicide) or Roslyn (surrender). As Roslyn is a major player, I'm sure others would behave as Gaeta (rebel) or Zarek (attempt a coup).
It is logical to turn inward and view your own misfortunes rather than outward and provide support to others and yet in the group is to move forward at all, we really need leadership to provide inspiration. While I sympathize for Zarek, he always seemed more interested in whining and grabbing power than leading. When did he ever really care about a group? I don't always agree with Adama's decisions either but if I were Zarek, I would state why, ask the needed questions and offer some alternatives. I never heard mention of plans to rebuild ships, provide self-sustaining water and food sources, provide education to young or most importantly continue to defend against possible future attacks. It is rather naive to assume that only Humans and Cylons exist in the universe while traveling so far. It is also rather naive to think that a military isn't necessary given that the Cylons are now in two teams and only one team is chatty with Humans. I wasn't surprized by Zarek's move and I'm glad he's out.
Gaeta obviously feels bad about losing his leg but like everybody else, he has to deal with rationalizing the past war, the surprizing turn of events and the many possible futures. Would he feel so angry at Kara if he knew that she had seen her own dead body yet hasn't been switched on yet so like Baltar, she is constantly questioning her own motives and behavior? Would he feel so angry at Adama if he knew that he had been friends with Saul for well over a generation, they had fought together and supported each other's personal lives only to suddenly discover that Saul is now the enemy? In a better environment, there would a ship's psycologist to monitor tensions and provide faith and hope. This crew even lacks spiritual guidance. Snapping and fostering a coup d'tat is not an unexpected behavior although in the end, it doesn't help anybody.
What's truly missing is a voice of reason, inspiration and hope. Where's Obama?