There's also a "rape" tag on the first page. Are you also going to try to argue that a group rape scene goes beyond the "rape" tag?
Blackmail is unpleasant. Someone being blackmailed into sexual slavery is even more unpleasant. Why would you think that playing an optional blackmail route would be anything less?
The game was never only about sharing, cheating, cuckoldry, or any combination of those things. They were present in the game, yes, but so was rape. There was a fairly hard-hitting rape scene in the very first release of this game.
The game was never about any particular fetish, be it sharing, blackmail, rape, or any other fetish. The game is about a sweet young girl who is going through a sexual awakening of sorts, but then gets mixed up in mafia business.
There were darker elements to the game from the beginning, and PaleGrass never hid the fact that the mafia characters were going to have a major part in the story. Anyone who was expecting the game to always be on the lighthearted side simply wasn't paying attention from the start.