Responses
Maybe because if he adopted yuta
Yuta can use his name ( surname ) rather than being married because in Korea even you are married it’s not necessarily or automatically you use the name of your husband ( i think )
And by adopting he can register him under his family registration
Same in OUR SUNNY DAYS mr. Kwon adopted
Sung Ho and the baby
instead of marrying him

DOES MARRIAGE NOT IN THEIR FUCKING OPTIONS I'LL ACCEPT IT IF IT'S ADOPTION TO BE YOUR WIFE