I like dramas which have u requited love from fl
Just you ( taiwan drama) however its in the past. He was gentle in past but got his heartbroken by his ex so he changed himself to angry / alone man. And fl falls in love with him 1st. It remains unrequited from fl side for few eps but ml and his past are revealed only later. Ml doesnt like anyone in present but however his past life and his ex had such an impact on him that he started hating Love ( Its revealed abt his past in later eps but its in detail, it shows how he proposed etc etc
Innocent lies - Again he loved his wife in his past, then he divorced cos his wife (the fl villain) was a psycho. But here both ml and fl fall in love almost same time
Loving never forgetting - I remember the fl falls in love with him 1st. And ml used to be intimate with another girl. Idk if he loved the another girl cos i watched it long back but yeah .
Husband in law Again he is a player not sure if he was in love with anyone else but fl was sooo into him
Pramook same as above
Backstreet rookie I think this one fits what exactly u r looking for. He likes another girl for long before falling in love with fl.. however fl loved and helped him for so looong
The Innocent Man
Also idk where u r from, but Majili( movie from india) also kinda perfectly fit this trope i think
Also feel free to recommend me any other dramas with fl loves ml first trope if u find any :) I find only some dramas are like that :(