I know, I wanna see her character develop more (๑•ㅂ•)و✧
It will also force Him out of the manor, since connections and growth for his character development would need to continue. There may also be an option that allows for Ibee's social status to "level up" so that marriage is possible in the future
Sadly, it is 100% necessary at this point, because she cannot really have a relationship with a 16-yeard-old, especially with the 16-year-old being the pursuer. It would rub the readers the wrong way. It's just not done in romance. Ergo, she needs to leave so we can have a timeskip to his 20s, at that point he'll be a fully consenting adult and she will no longer have the excuse of his age to keep him at arm's length
TBH ibelina leaving the Manor is the best option for the author. If she juststayed, itd be more of the same. To advance her character, Ibelina needs to leave and encounter other characters.