Yeah, its a general cultural taboo.
However, it does deserve to be talked about. Why do video games not have the freedom to show sexual situations? Virtually every other entertainment medium has an abundance of sex scenes, yet when Mass Effect shows as much skin as you could find in a late night TV commercial, its all over the news. Meanwhile, Hotline Miami 2 is banned from Australia for depicting a rape scene in Hotline Miami's pixelated style.
Some "think of the children" bullshit mentality has stuck into video games, despite the global rating systems which makes people get up in arms about sex in games (and even more so about rape in games) because children play games and that is something that policy makers, game makers and the game community all need to participate in moving past.