"Alliance" is something of a... loaded word. Take it from the former leader of Leicester. Yes, all the noble houses banded together to survive, but they were still vying for their own self-interests at the same time. Count Gloucester, for instance... He sent his son to watch me like a hawk, because Gloucester had one eye square on the leadership of the Alliance, all while he had a foot in the door of the Empire. Of course, he was worried I was the one who would betray the Alliance, so in his mind, it was the right course of action over blind faith.

Ideals like being noble in deed and loyal to one's word are all very well and good for Faerghus storybooks, but they usually don't translate to the real world. And if they do...

[He grimaces, his expression distant as he recalls a memory better forgotten. Well, no need to bring that up here.]

I digress. I think your view of things is admirable, Byleth, but loyalty doesn't really have any place in an arena where you can never be sure of your ally's true intentions.