Yep.
But Darka has been the exact same way. They've demonstrated they care little for anything except what directly effects or benefits them.
You're right. Eston doesn't care much for Darka. Darka backstabbed us and stole an entire duchy, what do you expect? Eston to be all lovey dovey toward you?
Thus is the problem with the northern alliance. It's a bunch of realms who don't traditionally get along, but are now allies of convenience.
I don't have a character in Darka, but damned if I don't like them better than Eston by now