That's because it was suppose to be this way. Ivy, basically, was a character exclusively for Lena path, only occasionaly and for brief moments crossing with Ian if he was in the scene. It's only because of her popularity among Ian players that she now gets some content with male MC.
I only got there around the chapter 9 rewrite, so I don't know how the first chapters were originally written, but Ian always shows interest in Ivy. On his side, she is clearly Jeremys
love sex interest, he is going after her for the entire game and Ian/Lena can help or stop him, but that doesn't stop Ian, doesn't it? Cindy is Wade/Axel love interest and Ian is setup to swoop him from the get go, Emma is mainly Perrys love interest and the focus can shift greatly on Ian, Lena and a bit of Jeremy.
Also, until chapter 10, Ian can interact with her around three times and gain relationship points, so why include them if there was no further plans?
Always wondered, why on earth anyone would believe that there was even a chance for it? It was clear from the start that ORS isn't about extreme fetishes, and from the first Seymour appearance - that he would never let anyone else touch Lena, if he is able.
Now I'm go to mansplain and what I observed and generalized doesn't apply to everyone, so it may not be gender/sex relevant.
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Generally, girls want to insert themselves in a story and become the main character, changing everything around them to their whims. Meanwhile boys are content to stay as an outsider and accept the rules of the story, they use the main character as a tool without needing to emphasize with them.
ORS two different point of views show this: On Ians side he "builds" his book and has to beat other men or convince other persons in quick time events. The focus is on winning girls and convincing other person related to his art, career and physical competition.
With Lena, the music and athletic options barely have gameplay. Her music or stalkfap path focus on her interactions with others, how they react on her. She has it far more easier to get every love/sex interest and the focus lies on how she feels about it, why with Ian it is a more challenging and competitive aspect to "conquer" a woman. Lena is also far more customisable regarding her past behaviour and present looks.
I hardly find a male equivalent of these really obsessive girls (who are a vocal minority) who greatly fawn over whatever popular man like Elvis, Justin Biber, Sasuke, Dr. Who, or Snape. They write elaborate fanfics in and build shrines and create an entire world in which them dating them is a natural fact. Boys may simp for girls and the most pathetic ones spent their life savings for them, but they rarely display that kind of "affection", it seems a more practical approach.
So in Andrea's case, she internalized her own sex life and sex fantasies (which she wants to display to the world, why else would she have a blog about it) on Lena. So whatever Andrea wants, Lena should naturally serve to experience it, ORS was supposed to be Andrea's outlet for her fantasies.
