There is a chance that they don't know the real reason. Conflict like this begins for a number of reasons that are forgotten over time. It's only grievances that continue to build and build until it becomes a cycle.

[It's the only sense he can make of it and the wars of his world. He had seen this before and even he couldn't say anymore why so many House were still fighting before Westeros ended.]

What will you do if they go to war?