I'm really confused... Annie and MC looks really alike. ( ̄∇ ̄") I'm slightly caught off guard but it's rather refreshing really, most manga would either make the MC really beautiful or ugly to the point that it doesn't match the setting of the story.
I'm looking forward to a beautiful friendship.. (⌒▽⌒)
I had a hunch it was the fourth prince. I mean, it make so much sense from a political standing. The king wanted war so he can 'unite' and 'conquer' the kingdoms. However, the first princess didn't want to but was threatened. The only one who would benefit from this is him. The betrayal surely and without a doubt was him. (︶︿︶)