Nice post (with a lot of replies so I'll cherry pick a few things)
This does seem to be one of the most popular pairings (or groupings) based on what I am reading. Given that it's been mentioned that there are going to be 20+ chapters and we're still in the early stages, one possible entry-point might be similar to
Lena x Axel x Cherry in Lena's past? Maybe Ian x Lena have to be fully committed and fully trust each other, yet want to spice things up. On the other hand, Holly has to be "changed" enough to accept being brought into a threesome.
Lol honestly reading the posts on this forum make me feel like the rare exception who has a strong preference for this pairing. ORS is one of the few games where my preferred route is full commitment instead of playing the field. I find their chemistry electrifying and explains their induced attraction to each other (please pardon this awful dad joke
). I do find the dual protagonist thing being the main driver for this, which helps explain their points of view on each other, especially when you focus on wits. At the same time I can understand because you control both, it can seem like... "onani-ecchi". But hey, I'm a sucker for dual protagonists with an intertwining plotline.
Picking the committed route however, the narrative in my mind comes across more as two people trying to stay true to themselves while struggling against temptation (Ian) or constant attention and attempted manipulation (Lena).
I kind of agree with BlandChili's view that there's a strong chemistry between the two, though I consider it the second strongest as Cindy comes across to me as being attracted to Ian because of his continued passion for life whereas she's someone who's trying to find that passion (and Wade is someone who has lost his, or never had it). That said, I don't really view it as the "corruptive" path, and I have my suspicions about the path.
After the birthday disaster, it does take a willpoint to stop yourself from doing anything to her, and based on the aftermath in chapter 8, you have definitely doomed their relationship by stopping yourself. This might culiminate in their break-up allowing Ian to enter? It almost seems like if you did kiss or sleep with her, all the tension has been "relieved" and now Wade and Cindy repair their relationship out of her guilt of what happened.
I do like Alison as a character, since her 'thing' to me is more someone who has had a thing for Ian for the longest time but does not know how to express it to him.
Her relationship with Milo starts after Ian is already in a committed relationship with Gillian, and she dumps her boyfriend after Ian is no longer in a relationship. Though there's actually a continuity problem since an earlier chapter says her boyfriend breaks up with her and a later one states that she dumps him. However, if you do pursue her path, it almost seems like she's self-sabotaging by constantly emphasising that she's not looking for anything long term.
It was actually a pretty enjoyable read! It also unfortunately resulted in a wall of text reply from me so my apologies as well.