I think Ian/Emma/Perry is one of several trios where we’re likely to see some kind of cuck/cheating/humiliation content. But as
dontcarewhateverno and
aykarin pointed out, the mutually exclusive routes makes it harder to imagine how it would play out in the strict sense of the term.
Though if we’re talking about cucking in the same sense as with Ian/Cindy/Wade, where the point isn’t that Wade will accept it and get some satisfaction from it himself, but rather to "steal" his girl and then make him unwillingly accept that
there’s nothing he can do about it, then yes, I think it’s a likely scenario. Ian is fully aware of Perry's feelings for Emma, so for Perry it will probably feel as a betrayal from Ian either way.
As of now though I think the by far most likely scenario for cuckold content is with Lena/Jeremy/Ian. In my last playthrough I noticed how explicit Ian’s inner monologue is about the voyeuristic aspects of watching Jeremy’s pictures. There's been a lot of talk about how prominent Jeremy's cock is in those pictures; however I think it clearly makes sense in this scenario. Ian's not just jerking off to pictures of Alison and Emma, or to Alison and Emma having sex, he's jerking off to pictures that very specifically show Jeremy fucking them. And unlike with Perry, Jeremy will only have sex with Emma and show Ian the pictures if Ian's already had sex with her. I think maybe his sharing of Alison pictures also requires that Ian shows some interest in her?
It would be a bold move from Eva to have one of the protagonists play the role of the cuck, but I think she would have a lot of strings to play on: Lena's exhibitionism and her tendencies to a cheating kink; Jeremy's and Ian's picture sharing; Ian's voyeuristic tendencies; the amount of guys that could be taking pictures of Lena in sexual situations (Axel, Jeremy, Stan, Seymour, her own pictures for Stalkfap); Ian's secret subscription to Lena's Stalkfap; and the fact that Jeremy really, really wants tell Ian all about his sexual encounters.
The obvious negative is the fact that Jeremy's such a bland character.