Yup, no one likes sudden tonal shifts. In this case, I knew the ntr was coming (in theory at least, I get the feeling I never actually tried to read the series because everything was new to me) via my memory and tags, but if you dropped something like that on me with no summary, no tags, just the title, my reaction not be positive at all. I thought you were talking about a specific trope for a moment there but then remembered the manga "It's Late But I Fell in Love With My Childhood Friend" and...what a way to make you turn on 2/3rds of the important cast. Like I'm not going to deliberate on it but that shit was entirely unwarranted yet extremely memorable to the point that remembering it makes me feel uncomfortable. One of those things where I'm pissed at the characters for reasons slightly different from the other people reading. Incorporate that into your narrative earlier, or at least give us warning signs; jeez. Maybe change the title to "I Fell in Love With My Childhood Friend But It's Too Late"?
In my case, I have never identified with the cuck, and have never met anyone over on the doujin sites that identifies with them. Everyone I know over there seems to cheer for the cuck's downfall and mind break, me included.
In the line of @panzerkampfwagyu said about harem protagonists, I detest worthless characters and NTR is a fine punishment for them. As Machiavelli said, "those who get power by fortune, by fortune may lose it"; change power for partners and you have it. Since Japanese bullcrap writers make tons of stories where those blank characters win everything with no effort, someone needs to destroy those fantasies by any means and as cruelly as possible. This includes generic heroes, that's why Alice Soft has been adding NTR for decades, because ass characters deserve hell.
All the unpleasant words have been picked up with care to add to the drama and making them as harmful as possible.
Yeah, it really depends on the context, in the end. The context being how good the romance is.
If, on the one hand, I see a pretty good romance between childhood friends suddenly become NTR, I as well feel disgust and stop reading with disappointment that the good thing was failed like that.
If, on the other hand, it's shallow romance, as seen with a lot of designated main heroines and forced harems that only exist because a self-insert MC was nice to them, then NTR is a very appropriate form of violence. Be it by having a character with actual chemistry appear, or by humiliating the MC with hardcore means.
Because, in the end, NTR is just a form of violence, with the morality depending on what it is executed upon.
Addendum: I've seen it once, but there also exists ethical NTR
From Wild Method (No chapters here), I won't spoil, but it turns the entire thing really wholesome. I'm serious.
In any case, I kinda think that NTR's reputation is pretty overblown. A lot of people seem to be anti-fans that deliberately interact with the topic despite hating it. Maybe it is a Moral Grandstanding thing or something like that, but they seem to get off on how great they are for hating an evil genre...
Addendum: I've seen it once, but there also exists ethical NTR
From Wild Method (No chapters here), I won't spoil, but it turns the entire thing really wholesome. I'm serious.
In any case, I kinda think that NTR's reputation is pretty overblown. A lot of people seem to be anti-fans that deliberately interact with the topic despite hating it. Maybe it is a Moral Grandstanding thing or something like that, but they seem to get off on how great they are for hating an evil genre...
Plenty of people just go to a certain title because of the cover just to repeat the same stuff over and over, be NTR or any other genre where no-life people can go and spout their moral superiority over a piece of fiction. The truth is, many of them do so only out of guilt and because it's their Internet persona. So one must piss them off as much as possible so they lose their will to protest (just like the NTR genre itself).
Addendum: I've seen it once, but there also exists ethical NTR
From Wild Method (No chapters here), I won't spoil, but it turns the entire thing really wholesome. I'm serious.
In any case, I kinda think that NTR's reputation is pretty overblown. A lot of people seem to be anti-fans that deliberately interact with the topic despite hating it. Maybe it is a Moral Grandstanding thing or something like that, but they seem to get off on how great they are for hating an evil genre...
It's one of those punching bags that's easy to use because it's not exactly like anyone is coming out to defend it (at least in the vicinity of where the accusations are coming from), and there is a social consensus that it is weird, that people can't understand it. I think it's no mistake that people always talk about NTR like the only people who are interested in it are people who want to be cucked: similar to furries, there is an interest in obfuscating information that would lead to better understanding the subject, as well as purposely pointing out the worst possible examples.
In the line of @panzerkampfwagyu said about harem protagonists, I detest worthless characters and NTR is a fine punishment for them. As Machiavelli said, "those who get power by fortune, by fortune may lose it"; change power for partners and you have it. Since Japanese bullcrap writers make tons of stories where those blank characters win everything with no effort, someone needs to destroy those fantasies by any means and as cruelly as possible. This includes generic heroes, that's why Alice Soft has been adding NTR for decades, because ass characters deserve hell.
All the unpleasant words have been picked up with care to add to the drama and making them as harmful as possible.
This does seem like the general consensus. I brought this up to a friend, as in the topic of this thread, and although they disagreed, they couldn't actually give a reason as to why besides "well I think cucks would still enjoy this" which made me have a thought: As I was saying earlier, from another perspective a revenge story could look similar to or exactly like NTR. Which makes me think that we might view a variety of different perspectives as all existing under the same NTR banner even though they differ in who they appeal to.
For example: The average "seasonal waifu gets corrupted after being blackmailed/seduced" doujin? That probably isn't designed to appeal to a "cuck", it's designed to appeal to the fantasies of someone who is a "bull". As we can see in this thread, there is a vested interest in wanting to see a blank slate MC suffer for some, whereas when it comes to someone who does enjoy that "no personality nice black haired mc" romance, they are likely one of the people in the "I hate NTR I hate NTR" crowd who would refuse to read it.
Meanwhile, you have the more classic "guy gets his crush/girlfriend/wife stolen under various means that wouldn't pass scrunity irl" hentai, usually beginning in denial that their love interest has not changed or that if they are aware of the situation that her willpower is strong, and ending with them witnessing the truth of the situation first hand and accepting it or embracing it, fully giving into the madness. This is often the kind where our "protagonist" has a noticably tiny dick, is scrawny in comparison to the "bull", and there is often a lot of demeaning language in relation to sexual prowess, and the protagonist may by the end straight up get turned on by being cucked or "cucked" (when it gets a morally gray or fully unethical due to drugs or something I'm not sure if I'm fine with calling that cuckoldry), possibly while crying. They might simply accept that their partner has been "stolen" and just leave them in a very "nothing I could've done" way. Sort of what people originally described as "NTR" before it seems to have evolved. This kind of makes me interested in a concept involving a person having their partner stolen by a Lovecraftian Entity, leading them to fully go insane at the end. Well, depending on how it's done.
There's the "Story Arc" NTR story where the love interest may be "stolen" for some period of time but in the end fully "returns" to the protagonist with possibly some consequence but not too much. This often borderlines on or is fully a non-hentai manga and may not share the same tropes as the others. I think this one is usually discernable by a protagonist who is not quite "pathetic" in the sexual sense but might be interpreted as pathetic by readers simply due to the NTR or cheating happening at all. I think this is the one that people often trip up on when they complain about NTR, for example Zebraman is a story where
the protagonist finds out his wife is cheating on him due to him being "weak", among a variety of other problems involving the rest of his family, but at the same time he is eventually caught up in emotionally cheating with another woman. Also he fights as a superhero (with no powers)
the NTR if it could be called that isn't intended for sexual gratification; it is a conflict in the story to be resolved but on a shallow level could be misinterpreted.
Then there are others which are harder to pinpoint: The case in which our "cuck" finds out about the NTR but leaves the relationship entirely in response or potentially even seeks revenge for example. You see this in things such as smutty isekai, "banished by the party", or other wn/ln adaptation-type stories. These feel similar to "Story Arc" NTR in that there's a good chance it could be being misinterpreted, like that one where the guy is banished from the party after learning his girlfriend is cheating on him with the "hero" and then we find out later that the hero has been brainwashing all the girls in the party; it doesn't track with the standard procedure of NTR (unless there are a lot of gratuitous sex scenes being left out of the manga) and even then this still is a story about the generic protagonist eventually exceeding the person who "stole" their partner, at which point in many cases they will simply not forgive their former partner, possibly let them die, etc. They are generally replaced with like...a slave or something; someone more obedient and devoted. In these cases, I think that's not NTR, it's a fantasy designed by someone who hates NTR; even the brainwashing, blackmail, etc. being included in the story being there more so they can say "the protagonist was never a cuck; they were always a great guy they just got tricked".
Another one that I fully don't understand the depths of is the "Female POV NTR"; There are a notable amount of women who draw NTR or at least hentai involving cheating even if I don't know the exact numbers; One that people seem to like on this site is Bear and Bunny Cannot Be Friends, which is sfw (ignoring the fanbox stuff) but plays with NTR tropes from a perspective that you wouldn't usually see when written by a guy. Not to mention all the erotic literature out there. There's sort of a theme of hidden desires, dissatisfaction in life or relationship if they have one, and moving of "fault" from the woman to the "bull".
To put it simply:
Bull POV: The narrative usually considers it the woman's fault for giving in; cuck is not the focus of the story; cuck is emotionally devastated but not compliant and may leave or give up; more focus on the bull and oftentimes the "stealing" could be underhanded or malicious but less likely to involve something like brainwashing or drugs as opposed to seduction (although fantasy and sci-fi creatures could be involved) ("She said she wouldn't come back, but she was hooked.")
Cuck POV: The narrative usually considers it the cuck's fault for giving up or accepting the situation; the cuck is significantly inferior to the bull in terms of strength, size and sexual skill; significant focus on the cuck's feelings and perspective; woman in most cases is sexually but not emotionally dominated; more likely to involve fantastical aspects like brainwashing, drugs, or other means that make it functionally impossible to stop the NTR despite the love interest loving them ("The sex chip that is mandated to be inserted in every woman has changed my relationship with my girlfriend, but I still love her...")
Story Arc: Could sometimes be something else mistaken for NTR; The narrative may apply blame to the cuck, woman (I would say hotwife but I'm not sure if that would be the right term), bull, or any combination of the three; the NTR may be an inciting incident but it is either not the focus of the story or if it is may not necessarily occur throughout the entire story; regardless of NTR, the story is more likely to have a happy ending for the cuck, whether it is with the initial love interest or with someone else; grab bag of exactly what leads to the NTR, especially if it's not the central narrative ("After a long quest, I defeated the demon lord and saved my fiancee, although it seems that she needs time to recover from the experience; she refuses to discuss it...)
Female POV: The narrative usually considers it the fault of the bull, the cuck, or both for seducing the female lead and not satisfying the female lead respectively; more likely to involve fantastical aspects like fantasy or sci-fi creatures with abilities that a human couldn't possibly match; less focus on the cuck's reaction and the cuck is not seen as often in the story; more focus on foreplay ("I said no, but I couldn't help it, it felt so good and I haven't been touched for so long...")
I feel like the more I am in this thread the more comfortable I'm beginning to feel with writing in general, so that's a positive.