Honestly I don't even care about the character troupe itself, she could be totally normal and I would still be annoyed just by the fact that the author decided that the Ai-chan story is more about her friend than the couple at this point, even if some other couples are stuck in development at very least the chapters is about them.
The author should just make a romantic interest for Volleyball-chan and make her disappear from Ai-chan storyline with small cameos rather than making her grab her boobs for 5 pages every chapter, with how the author uses her she somehow is more one dimensional than the Teacher that literally doesn't have dialogue.