It seems the real cuck in this game is Bob, seeing as the NTR is completely inconsequential. Though considering everything else in this game lacks any real sense of weight or climax, that fits. I didn't even realize I'd already beaten the demon Jack was supposedly summoned to oppose until hours later, it felt like a sidequest.
Too bad this game likely won't get any more updates to flesh things out a bit more, fix the remaining bugs, and finish the translation. Maybe I'm just greedy for more Krista content...