For an anime adaptation of a romance game, Hakuouki really has very little romance in it. This is not really surprising since the visual novel it's based on, for all that it is a romance game, is much, much more about Japanese history and samurai politics and philosophy than it is about romance. There's romance in it - although my first pass through, I somehow managed to avoid all of it - but it's really not at all the point.
The point instead is mostly this: a handful of farmers' sons and other rejects and misfits collected around a dirt-poor dojo devote themselves to becoming warriors, forming themselves into a fighting force with the intention of earning recognition and attaining their culture's samurai ideal, and to hell with anyone who says they can't. They claw themselves up from the bottom, get within spitting distance of their goal...
...only for the times to change. The cultural goalposts get moved on them; the skills and the way of life they devoted everything to become obsolete, and the goal they sought to achieve is suddenly meaningless. The government they served loses its power and collapses, throwing them under the proverbial bus of a war that can't be won.
So, you know, what do you do?
( 'I am not going to battle to win. With the Tokugawa government about to collapse, it would be a disgrace if no one is willing to go down with it. That is why I must go. I will fight the best battle of my life to die for the country.' -- the actual historical Hijikata Toshizo, to Dr. Matsumoto Ryoujun, according to Wikipedia )
All of this Bakumatsu period stuff may inspire me to finally get around to watching Bakumatsu Kikansetsu Irohanihoheto. We'll see!