Now, here is where it gets tricky. Ian wants it, but Lena "considers" it but then refuses. So, what happens to the Ian side of the story? Does he 'go away skulking" because he can't get his 'cuck content' or pretend that the whole thing never came up and continues on his way? You see where the 'wasted time and effort' comes into the equation? And I'm not talking simply wasting time and effort as a player, but for Eva who would have to literally stop the ENTIRE project just for this one moment of 'fetish content' that has vast outcome results without moving forward on the actual original story. It would bog Eva down with focusing time/effort on "side content" with little or no time available for "main content". And that is for simply ONE of several possible "cuck content" possibilities.
There is no "side" or "main" content. It's all your choice. Your active storyline is the MAIN content for YOU only. Check the last update for example. It was mostly Holly-focused, while Cindy took a backseat. Is it disappointing for Cindy fans? Sure. But next time Holly (or someone else) might take a backseat while those who pursue Cindy enjoy themselves.
Ian and Lena can have various types of relationships. You could argue the same things about their VANILLA loving relationship. Why is it in the game if the player won't see 80% of the rest of the game (Robert, Mike, Axel, Cindy, Alison, Cherry, Holly, etc)? Because it fits into the concept of MULTIPLE CHOICES. Just like the player could decide whether Ian loves Lena or Lena loves Ian, or one/both of them treat it as a casual hook-up... I'm sure the same can be achieved with potential voyeur/cuck content as well where the players decide how each of the characters feel about this kink. OR, their reaction might be decided based on a combination of your past choices.
For example: If you previously asked Jeremy to send pictures of Alison or/and Louise, thus triggering his voyeuristic kink, it might give you an opportunity to ask Lena about it. And Lena's response would depend on your playstyle as well. Is she faithful to Ian? Or has she slept with any of the guys/girls? Does she have an exhibitionism kink? Did she have sex with Jeremy? Any combination of those factors might trigger her positive response without giving the player an opportunity to decline (because she would want to continue cheating, and cucking Ian would give her the opportunity to do that openly). Or, if Lena was exclusively interested in Ian, but he has been dominant with her and she has a sex-slave fetish, then she would probably obey his kink as well and would fuck anyone "her master" commands her to fuck. Otherwise, if she has a very low Lust value, she would auto-decline. In other instances, she might "consider" it, and then you can decide as Lena if you want to pursue that and try sleeping with other guys (or girls), or you could tell Ian that it's not really something you're interested in, but that might still open some role-playing and teasing opportunities. Lena isn't prude enough to break up with Ian over some fantasy.
But knowing Eva, the cuck content would probably be triggered in one of the Ivy-related events. If they have another sexy game, with Ian participating, Ivy might want to test their relationship and tell Lena to do something sexy with another guy while Ian would have to watch (or the opposite scenario with Lena watching Ian with another girl). And that might lead them to reflect on that experience and their feelings that would develop or lock that kink.
However, whether or not to do all that content with lots of additional branches, it's up to Eva to decide. If it proves to be too much for her, she probably wouldn't do it, though it would be a massive wasted opportunity. No need to tell others to stop talking about a particular kink that might fit into the narrative, because it's kinda rude. Just because you think ORS is "too developed" for that, it doesn't mean that Eva necessarily thinks the same way.
Stan? I am not sure about Stan at all. The only way that I can see that one happening with Axel is ONLY as either 1) A "warm up" for more dominate male figures, or simply as 2) Some kind of "test" to see how submissive Lena has become by basically accepting any partner into the bedroom. Even as a 'test', I can't see Axel simply sitting aside and watching WITHOUT getting involved himself and turning the situation into a 3-some more than basic 'cuck content'. And in regard to the 3-some option, Axel would clearly be the "dominate figure" involved with Stan/Lena/Axel, almost to the point of being cruel and aggressive towards Stan just to get rid of him.
Why do you think that a particular kink needs to be equally applied to ALL and ANY characters? Clearly, some character types are "locked into" scenarios that only their path unlocks. Obviously, there won't be any "cucking Axel" route or "cheating on Mike". Mike has a cheating fetish where Lena is the other girl in the relationship and his poor girlfriend is in the dark, while with Ian it doesn't work like that at all, she at best tolerates the other girls in his life, and some other girls, like Holly, end up breaking their relationship. Eva cuts corners by making some paths character or other path-exclusive. In GGGB, Ash could have a threesome with Eva and Dave only if she broke up with Eric and Eva is not a slut anymore. Dave content was the same, you needed to be single to date him. You couldn't cuck "Alpha-Eric", only have an open relationship with him. As you can see, there is some wiggle-room for Eva to include potential kinks into the game, she's been doing it for quite a while.
Scroll down a bit after that post and you can refer to my reply there.
You have a wrong interpretation of what "cucking" means. You can't be a cuckold if you're not in a relationship with a girl. Just because a girl you have a crush on started fucking or dating someone else, and you feel some jealousy, it means just that, that you haven't moved on. Gillian broke Ian's heart by cheating on him, but it's clear that he still has some unresolved feelings for her because thinking about her makes him sad that he lost her, not angry that she betrayed him. Does it make Ian a cuck because Gillian is enjoying some other dick in her private life now? No, it doesn't. And cucking is always voluntary. If he starts dating Lena for real and she cheats on him, it would only make her a cheater. Ian would need to know about it, and consent to it for him to be a cuck. Otherwise, he's just a victim of the cheating. Perhaps a fool. But not a cuck.