He can understand why it bothered her to watch the first few times, but, he thinks, rolling his eyes as she retches slightly at the first sound of breaking bones, enough is enough. This isn't new to her anymore, and if she's not used to it by now, she never will be.
As long as it doesn't convince her to do something stupid, like put his plans in jeopardy because her conscience is getting to her, he supposes it doesn't really matter if she likes it or not, but it would be kind of nice to have someone to enjoy this with. It's fun, and it's satisfying, because the death count is a measurable way to track his progress toward the success of his plans. And he wonders angrily why she can't see that.
Or at least, why she insists upon trying to ruin it for him.
So later on, when the mess has been cleaned up and that greenish tint has left her skin and that look of cringing, disgusted fear has left her eyes, he tells her:
"I'm not gonna let you watch anymore if you keep looking so miserable afterwards, Mirage; you take all the fun out of brutal violence."