"Desensitization" happened over the years when it comes to violent movies as well. Many movies from the 70s and 80s were deemed to be to be too extreme back then and today nobody really cares. Evil Dead was banned in Germany for quite some times and now you can see it as long as you are 16 or older - even in Germany which probably has the most extreem youth protection laws one could imagine. The reason for this is that people are used to see this sort of FICTIONAL violence now so it does not shock them anymore. However they are aware that it is just a movie. The same thing does NOT apply to the real world. You won't go out, see a person ripped to shreds and say to yourself "Oh, I've seen this in Evil Dead - it does not shock me".
So as long as you are aware that this game is only telling a fictional story how could it desesitize you for real events? Both things are completely different. I mean - this is not even an actual game in which you are allowed to control your character and even though the render do look pretty good they are still far from looking real. You are basically watching a storybook with some animated scenes in it about a pretty dark story with a psychological background. So why again should I now have any more desire to go out and abuse women just because I watched a storybook about a sick kid and clicked on some choice buttons to branch inside the story?