Here is a small spoiler for you all. When Taeyong got transfer to Seoul, His parent barely talk to him due to their business. So they hired someone to take care someone for him and he dont like that.
Time past by, Taeyong studied in SOPA but its just in mean time cause he always gets in trouble. Taeyong always had a fight, he skip classes and he had no friends.
One time, Taeyong was scolded badly by his own father because of his bad attitude, he run away and got into an accident.
At that time, his memories went off and on. That's why he cant remember Seulgi but his brain ache a little whenever he look at her.
As for Seulgi, she just had a bad memory nothing is problem aside her bad memory. She easily forget things.
