to be fair the male characters seem to have enough differences for players to check on their story/scenes
Alison and Cindy seems to have a lot of variations in their story depending on how Ian treat them.
iirc Alison really loves Ian and tries her best to get his attention. Ian almost need no effort to claim her. If Ian choose to focus on another girl and break her heart then he should face the consequences. But keep in mind that even after the scene you mentioned had happened, Alison still wanted to return to Ian. All Ian needed to do was to tell her he wants her.
you really cant blame Alison if Ian makes the wrong move and send her the wrong message.
Cindy and Wade had problems for a long time. It's just a matter of time before they break up. You saw those Wade scenes, perhaps he used to be different but now he's so flawed. Cindy liked Axel the first time she saw him (stupid I know). Technically Ian is trying to take Cindy from Wade and Axel. Cindy knew Ian for a long time and nothing happened. They never had the spark. It's meant to be difficult for Ian to make Cindy fall for him but if he makes the right choices, he still can.
I just want to say while there are lots of porn logic, most of the events happened because of your previous choices. and most of the choices are quite obvious if you are just going for one romantic partner. there are also many paths to explore, if you try to get all the scenes in one play througth you will make so many "wrong" moves and those "cheating" events with Alison and Cindy are doomed to happen if you pick choices like that. If Ian is not loyal then don't expect women to be loyal for him.