Though secret seven is not BL, it's also about the main character finding out who is the real guy?
In secret seven I think the female lead gets gifts from a male. She feels it's one among the seven guys.
Secret Seven (2017)
Similars
Both are a guessing game. In Reply 1997 you are guessing the husband and in Secret Seven you are guessing the Secret admirer. Both also feature 90s music. Reply 1997 is more serious, while SS is more like a light hearted game.
Both have "reverse harem" genre with handsome male leads ................................................................................................................................................................
Both have "reverse harem" genre with handsome male leads ................................................................................................................................................................
Both have "reverse harem" genre with handsome male leads ................................................................................................................................................................
Both have "reverse harem" genre with handsome male leads ................................................................................................................................................................
Both have "reverse harem" genre with handsome male leads ................................................................................................................................................................