I'm not sure if this is a bug, but whenever it comes to the sex scenes, the SFX is linked to music volume, so you're just forced to listen to the music in the background with the moaning. I noticed this when I had the music volume turned down, but everything else was turned up, and I couldn't hear anything, only to find out I had to have the music on to be able to hear anything. I do like to listen to other music in my background when playing, so it's a bit funny to hunch while listening to ambient choir music