Considering that there is no option to be disgusted and disappointed in the moral principles and good manners of your older sister, turn around and walk away, sending this cheating filthy whore into ignore for the rest of your life, you can only watch and jerk off thinking, that you wish to be in his place!! at least you don't want to be in her place, thank you for that. It looks pretty much like being tied up and forced to watch your future LI get fucked by some bull and all you can do is to miserably jerk your little cock.
Im not sure why the game did it in the first place.
My first thought it was "just" a sex scene for the whole purpose of demonstration of what the game has to offer Animations wise.
The game didnt even make it clear if it was a Dream or it was a "Time skip". But yeah, Im not gonna lie not every one likes the Idea to see your own Older Sister banging other dudes in a porn game where she is one of the FMC.
Its odd why you can have different "options" to chose who and how you want to look at different girls during the game (or even avoid them) but this once scene is forced uppon you. So yeah, if you dont have a cuck or voyeurism fetish this will impact you and your judgement of the game.
Personally, I dont mind that other girls (yeah, even FMC) have sex during the game with ohter guys BUT ONLY if the game makes it clear that you gonna win her over during the game. In this game however I dont really know for sure since this whole RR-Meter mechanic isnt a "romantic" or "corruption" path but it locks you out from different girls.
