To be fair, I think they didn't mean to. It doesn't really seem like "backstabbing" or whatever, but something that Mr. Mole seemed to just brought up. I think Mr. Mouse was just too nice to not answer him, and judging by his body language, actually feels rather uncomfortable talking about it behind Mr. Croc's back.
Calm down, people. Croc just became pensive. He's been going aimlessly since he quit his job -or before that?- so it's normal he'll feel bummed that his friends underestimate what he's going through. Hang in there, Wani!
I have a feeling this is someone's personal life with anthroanimals acting it out. This looks like what someone suffering from a mental or emotional illness may go through