There's a good scene is the TV series Des where the investigator interviews an phychopath who kept the dead body around and watched the TV with it in another chair. The investigator is interested if Des had sex with the body. To which Des asks who's the real sick person here if murdering someone and pretending to interact with them is ignored, but potential sex with a dead body is what warrants attention.

Reminds me of the GP comment... Also aligns with - murder is so out there that we can joke about it, rape is so common that we can't.

Because sex is something that most people are going to engage in at one point or another, it's part of human nature. Killing and murdering isn't acceptable.