>>715043694The existence of the cuck is to allow the character development of the bull hero and his love interest, or the female protagonist and her manly love interest.
>>715044101 is right, the cuck always plays the antagonist role in NTR media. The bull and woman are the ones who advance the story and undergo changes from the beginning of the story to the end. The cuck only exists to oppose the advancement of the plot, i.e. to act as the antagonist. The cuck is always defeated by the climax of the story as well, and usually in the final scenes his opposition is crushed. This is the resolution of the story's central conflict, the protagonist(s) triumphing over the antagonist.
In cases where the cuck "wins" essentially nothing changes from the beginning of the story. There effectively is no story, because nothing happens. This demonstrates that the cuck is an antagonistic force, opposing the actual drivers of the plot, the bull and the woman.
I think this is why some people get irrationally furious about NTR stories. It's a genre where the POV character is the antagonist. They get tricked into identifying with the dragon and become butthurt when the hero slays him and takes the princess. Then go on 4chan and project their own insecurities all over the antagonist and saying he should've won, when he was written into existence for the express purpose of losing.