Poor boy, he cares so much for his fragile mom (his dad's words) that he's forcing himself to keep away from what he loves the absolute most, cute things be it objects or clothing, and being cute by wearing cute clothing. I bet this is killing him slowly inside, but he's too concerned about his friends that he tells them he's satisfied and ok while trying to force himself to believe that it's true.
If it hadn't been for the fact that his mom is so fragile about him liking cute things and such, he'd be dressing in cute girly clothes all day long, using cute backpacks and pencil cases, and anything else cute that he ever wanted, and Aoi knows this, and is smart enough that she probably already figured out that it's his mom that's the reason for his sudden change. Aoi just wants him to be who he really is, and likes him no matter how he dresses, acts, or what he likes, but can't accept how much he's likely suffering on the inside from having to force himself to stop liking or acting cute, etc.