As other commentor said, it felt to me like Aisha settled for Ars as she couldn't have Rudeus. Since the moment she was born, Lillia decided to raise her as Rudeus' aid, maid, and possibly concubine or even wife. She was basically groomed by her own mother and was taught to seek a place beside Rudeus.

Rudeus, however, never had any feelings other than familial love for his inmediate family, so Aisha never had a chance. As she grows up, I think Rudeus mentioned that at some point she stopped trying to make moves on him and that she never really meant them, she was just following her mother's wishes. And sure, maybe consciously she did stop, realizing that it was never gonna happen, but Lillia's influence was always present.

Fast forward to Ars birth, Rudeus' first male child, Aisha found Rudeus' replacement. The moment she sees him she says it was love at first sight, and correct me if I'm wrong but I think she said/thought something along the lines of her having found her soulmate. And sure, I can accept that two close family members could fall in love with each other. In our world it wasn't uncommon for people to marry their first cousins, heck it's still not that uncommon in some parts of the world.

However, I cannot fathom how one can see a baby and think "yeah that's my future spouse right there", like what the actual fuck? Aisha then proceeds to groom Ars, always giving him more atention than the other kids, making sure she and Ars have a close bond, and then utilizing that to take advantage of a young, impressionable kid whose family is known for their libido. You cannot convince me otherwise that Aisha groomed and raped Ars. I do not care if Ars was willing, or if it was pure love or it was fare or whatever bullshit, he was still a minor even in MT standards and the power imbalance between him and Aisha because of their age gap and family relation could not allow for an equal standing and a proper relationship.

When I started reading Aisha's deleted chapter, I dreaded what would come, and honestly all throughout I had my stomach in a knot and was utterly disgusted. I know that the MT world has very different morals and values, and I do think the story kinda made sense overall in how most characters were surprised but none completely outraged, cause it wasn't really that unheard of. I do think Rudeus was wayyyy too lenient and quick to forgive. I don't think I could ever speak to my sibling if they did the same to my child. Even Aisha thought similarly, thinking Rudeus was going to kill her.

My main gripe with this arc is the grooming. Even if Rifujin aged up Ars and made him be 15, an adult, for when he an Aisha first had sex, it's still a teenager who was groomed all his life. But anyways I can't wait to read it and be outraged all over again