Vicenna is crumbling. The mountains in the distance appear to be gone, which should be REALLY weird and scary. The Knights and King are closer to the river, and closer to Areta. Which as far as you know may not be as unstable as Vicenna.
It's hopeless to stay and fight and I was actually HOPING everyone would run. I can't stress enough that the earth is about to completely collapse. Staying to fight in spite of that is suicidal.
That, and regardless of what's happening, you'd think a knight who's fanatically obsessed with his King would, in this moment of utter chaos, cling to the one thing he knows: protect the King at all costs.