I was going through the House of Ballads questline today, and took it all the way to the final showdown with the Maid of Windmyre. The whole time, I was as threatening as possible, choosing the "I'm going to kill you" option whenever she showed up. I got in battle with her, and towards the end, activated Reckoning Mode (guitar squeal). I beat her the rest of the way down and prepped for the camera shift that comes with the special kill. What I didn't know was that there was going to be more dialogue at the end. I was already hitting buttons when some options came up. Next thing I know, she's telling me how alike we are, and how she'll prepare things for our future. I chased her around the hall swinging my chakrams, but it didn't matter.
So, yeah. I gave the entire House of Ballads over to the bad guy. I think I'm her lover as well.