My two cents as someone who does not like NTR and this games contents.
In this game, you the player make decisions and those decisions determine your future choices and the outcome of the game.
Only the players choices determine whether you will see the MMF/sharing.
If you do not choose the previously mentioned options earlier, the dream will not be seen by you at all.
I know this because I have played without using a guide with all of the decisions being my own choices and the dream never happened.
The game is amazingly well done, and it actually unlike some other visual novels, gives you the players the choices that determine the outcome of the game and what content you will see.
So please, if you do not like NTR, or as is the case in this game ,sharing, do not cry, scream or whine at the dev about it on here, because it is your own damned fault that you got the dream episode and no one elses.