I don't understand how people say the progression isn't covered well if you choose the sharing options. The fact is though that D has three fairly large influences when it comes to sex. F, Elena and porn. Elena is trying to get D to open up in the early chapters but it wasn't working until F helped break down those barriers that D had built up over the years. Then, F introduces her to porn. She had never watched porn before and Mr Dots uses the choice of porn to help shape D's path through the game. Not just sharing with other men, but women and even her friends too. The threesome scene with D and Elena is a choice that can be effected by the porn D watches. Now that D is more open, Elena is able to push D's boundaries and into the more kinky stuff.