I feel bad for the grandpa.
She is clearly not gonna win over Mone-san who has an assured win with the only named guy in the manga.
And like all other side girls in harem manga, she will remain single into her late 30s, becoming the alcoholic auntie that teases school boys from time to time as a defense mechanism for her lack of love life, she will end stuck as the gym class teacher or nurse playing support cast to her students, and despite still being hot everyone will call her a hag because everyone else moved on and she is now surrounded by kids.
Then she will fade into the void and will never be seen again, until she appears at the wedding of her students as a background character then it is back tot he shadow realm with her, ironically she will share the same fate as the typical male support character in a harem manga.
A tale as old as time.
The grandpa will die without seeing his great grandchildren, what a dick move to introduce his dreams and aspirations author, why gotta do the old man dirty like that?