Both are BL dramas whereby the main character and his love interest initially do not have a properly defined relationship. They have a sort of friend with benefit situation under the guise of the love interest 'helping out' the main character. My Stubborn is a Thai BL drama and Secret Lover is a Taiwanese BL drama.
The similarity in both Never Forget Your Enemy and Secret Lover is that the main couples are childhood friends that turn to lovers. Also, one of the boys secretly keeps girls from approaching his friend by dating them. It started as a requited love then they became boyfriends in their later years after high school.



