It seems that it's a trait of those from the Xia family. They aren't usually close to others, but once they accept someone, they can get along with them just like Luo Ai'ai does.
Unfortunately, no one has earned Xia Youyang's approval yet, so he remains alone to this day.
While it's fine to be alone, Xia Liyou insisted on giving him a task, which is to invite his classmates over as guests, claiming it's to celebrate his birthday.
Xia Youyang repeatedly declined but couldn't evade Xia Liyou. In the end, he ended up going to school with a pile of note cards that Xia Liyou had shoved at him.
Xia Youyang can off anyone except, it seems, Xia Liyou.
Unable to articulate his contention nor able to assert himself, and unable to ignore her altogether, he was eventually left at her mercy.
