Although Renji did not know "Momo's" specific identity at that time, based on the fact that she could trigger a special quest, she was definitely not simple. So after accidentally selecting the fourth option, fortunately, he had the good habit of saving the game and decisively chose to reload and select again.
As for why a healthy game would have an option like "option four," Renji thought at the time that the game used this method to hint at "Momo's" Succubus attributes.
But now, after shooting the movie and realizing the game's scenes with real emotions and scenery, Renji has vaguely guessed something.
Lena learned about Suthia, Nova, and finally the maid Zero during her infiltration of the Ashen base, so she would have reasonable "fantasy" behavior in the later stages, combined with "reality."