Nah I think the author had many ideas for characters and for the main characters. The author decided to use there chapters left to add the characters she wanted instead of developing the main couple. I'm happy that they did because we got our favorit girlfailure Andou.
Unless I'm missing something. These are 5 siblings and the middle child, a girl, likes the only son of the family. I'm happy about the first part but not the second part.