upt i watched it (spoiler alert for oshi no ko episode 1)

my barns and noble didnt have the first one so i watched the first episode and HO-LAY it was 1 HOUR heres what happens. so this doctor is a fan of the idol ai from, a kpop group but like creeply, when she goes on hiatus she comes to his hospital P R E G N U A T at 16 they become friends i guess? but on the night shes meant to give birth to twins her stalker kills the doctor. and reincaranates as her SON i forgot to mention hes a fan bc of a 12 year old cancer patient who loved her, weridly the kid wants to marry the doctor and this fully grown man says he would if she was 16 she kid dies tho and the year shes meant to be 16 ai comes in and the kid becoms the daughter, they grow up together trying to help their mom become bigger in the indersty for more oppertunitys but before she turns 20 the same stalker who killed the doctor shows up at her door with some flowers. ai gets flashbacks but then the stalker stabs her, calling her names and telling her that because she hid she had children she broke his heart. and she dosnt get angry. she explains how lying is a form of love to her and then she DIES in front of her children the reason he had the info to know everything from the address is because of the mfa father who gave the info away after ai tried to get him to see his own children. my question is how old the father is and why, im honestly flabbergasted at this because ai is the face of this show/book