Not exactly. A "cuck" is a blanket term which is not clear what it implies when the players go for it. Because for me "cuck" means cuckold, a person who knows, accepts, and even encourages the sexual adventures of his girlfriend or wife. So, Ian who simply takes pleasure from Lena's sexual escapades outside of their relationship. It might not mean because Ian wants to be reduced to a useless wimp that never has sex with Lena or to even enjoy humiliating remarks like "other guys fuck me better", etc (or at least not headrush into it right in their next scene together without any sort of buildup and discussion of boundaries).
Personally I picked that option because in my headcanon Ian partially feels guilty for why his relationship with Gillian didn't work out, so with Lena he wants to be more open and supportive of her clearly insatiable sex drive, he doesn't want to be boring like Wade or jealous and controlling like Axel because those were clearly dysfunctional relationships. He wants to give Lena pleasure, even if for some weird reason the idea of imagining her with other guys turns him on. If you make Ian watch porn in the very first chapter, he goes for the MFM threesome with a redhead girl that reminds him of his past flame... So there is potential for Ian to be aroused by at least a possibility of sharing his love interest with another guy (or at least in fantasy), or seeing his love interest have sex with other guys. He could already be a voyeur with with Alison by enjoying the pics and vids that Jeremy sends him. Note that Jeremy doesn't humiliate Ian for his voyeuristic kink, he simply gives his bro what he wants and respects his boundaries (he stops sending them if Ian is not into it). So, maybe Ian is just a voyeur and the idea of Lena being with other guys turns him on. It can be triggered by insecurity, sure, but it doesn't mean he enjoys feeling insecure or is ready for Lena to abuse his arousal without any regards for his emotional state.
To emphasize, if it was clear from the start that the cuck path implied "wimpy, submissive, sexless Ian", then I wouldn't have a problem with it if it was clearly telegraphed to the player (well, I would be personally bummed out because it would be a repeat of Ash x Cuck Eric from GGGB). But even if that was intentional to be that way, "ian_chad" and "ian_lena_dom" variables kinda make it hard to buy that a sexually confident and dominant Ian is suddenly okay with his "cuck" role and accepts Lena's humiliation without retaliating and fucking the living shit out of her so she remembers that she belongs to him (like she told him several times when Ian fucked her hard). This switching of their dominant / submissive roles would be very hot and add a very interesting layer to their dynamic. It makes more sense for Ian to be a self-respecting voyeur on the cuck path if he's a Chad or simply confident in himself than to suddenly go all meek and accept the ultimate humiliation of being nothing more but a worthless cuck. Imagine if a confident cuck Ian could share Lena with Jeremy just like he can casually share Emma, and tell him that even she's his girlfriend, he wouldn't break their bro code if he wanted to fuck Lena whenever he wanted. I don't see it being possible in a simple open relationship path without a "cuck" flag being active.
My problem isn't so much with the lack of option to back out as Ian, but with how Lena starts automatically treating Ian. She's the protagonist, but her agency is stripped away for the sake of Ian's one single choice. Even if she was all love-struck about Ian before and was always faithful (we're not victim-blaming Lena who fell to Seymour's blackmail), it takes one dialogue choice in Ian's POV and she's suddenly a mean bitch to him for no given reason, like that choice single-handedly rewrites her character. Now, if the player could choose, as Lena, how to react to Ian's newfound kink, and either be more dominant and cruel, or stay more loving, playing into his fantasy but never breaking his trust, then it would be more fair. Imagine if when Ian confessed his love for Lena to Jeremy, the game automatically assumed that Lena reciprocates (because it's a player choice to initiate something between them). But we had an opportunity for Lena to have agency of her own, and not reciprocate his feelings, and it unlocked a very interesting opportunity. Same when discussing Ian's threesome fantasy, Lena can agree to explore, or shut it down (even if she shares his fantasy). I'm just saying that a cuck path could very benefit from better writing that accounts eitiher player choice to decide how Lena starts treating Ian, or to make the shift less abrupt and have several stages, where the more teasing Ian tolerates, the less respect Lena has for him.
