On the open route, Jeremy is almost certainly going to be the other male, for Lena's probable MMF threesome. I mean who else would Ian choose? But that's more sharing than cucking. Cucks watch, they don't actually take part. In any case, the cuck route isn't part of the open route. You have to be on the relationship route, where Ian and Lena decided not to open things up, and then subsequently Lena starts cheating on him. On that route, Lena doesn't allow Ian to fuck her at all. He has to settle for handjobs, footjobs and the occasional blowjob if he's really lucky. She's basically training him to accept whatever she decides. My guess is, Lena's cheating/cuck path will eventually have Ian choosing whether to stay with Lena and become a willing fullblown cuck or ending the relationship. On the open path, they'll probably end up as swingers and/or allow each other to sleep independently with other characters. I think Mike, Jeremy, Mark, Jack, Ivy, Emma , Jessica and possibly Louise and Holly ( bad girl mode) are characters who would very likely go along with that scenario.