I'm interested to see if these two paths will be possible for Ian and Lena.
The first would be Ian cheating (may not necessarily be cheating because Lena could reject Ian) on Lena with Cherry and Cindy, and tempting Lena to a "foursome" arrangement. Lena has a bad history with Cherry and currently beefs with Cindy, so that would be challenging to achieve. I imagine this would require very specific decisions. The only possible way that I could see Lena accepting this would be if she is also cheating on Ian. We can already see Lena learning about Ian fucking Cindy, and although she doesn't take it well, Ivy can remind Lena that she is a hypocrite for also fucking people behind Ian's back like Mike, Jeremy or even Axel and that softens Lena's judgment on Ian. It would be interesting to see the role that Wildcats subplot has on this. Lena can also be a raging lesbian and she can have that magnificent hate-fuck with Cherry and Cindy. Lena can also have a budding relationship with Holly, and Lena is already imagining a relationship with her and Ian together - add this with Holly having feelings for Ian and this can lead to Ian having more cake. I really wish Cherry has more role to the story like Cindy with Axel and all that. The only side chicks who are woven well in the plot are Cindy and Holly. The rest are just not that significant. Cherry had the potential to have more but it seems the dev didn't explore this.
The second would be Lena cucking Ian and stealing all his girls. We can already see the possibility of Lena doing this with Holly, and if Lena is also fucking Axel and Mike, then you can see where this goes. If not Holly, then Lena can learn that Ian is cheating on her with Cindy and Cherry. Cindy is already slowly falling for Axel and it wouldn't be that hard to convince Lena to have a threeway especially as a way to get back with Ian. Lena already had a threesome with Cherry and seeing that Cherry hasn't fully moved on, can be enticed to have her past dream arrangement with Axel be a reality. At this point, Lena is already addicted with Axel again as she can't refuse him. I see Lena being convinced with the whole "starting again" thing that Axel is selling, and making Lena actually be the one to propose this arrangement to Cherry. I'm sure Cherry would be happy to finally be forgiven by Lena, and be given the chance to have her cake and eat it too. Cherry would be reluctant and suspicious but a Lena with a high charisma would be able to persuade her. Finally, it is likely that Gillian is Mike's girlfriend so Ian seeing her ex with his current girlfriend, Lena fucking the guy that Gillian cheated with is the ultimate cuck ending for Ian and revenge for Lena.