Why it was failed?
Me too, i learned korean just to fill my free time. But i found it pretty difficult hehe. Because now i have to learn Arabic for my studies.
Honestly i love them all with no different. But you can say i love Jin and Taetae a little bit more than other. That's why i read Taejin Fanfic the most, but really i love them all.
And no, i don't like any other k pop groups. I don't know why. I love BTS because they have given me a reason to live my life.. and their songs gave me a strength that i lose before. *ugh sorry for my english, i hope you get what i mean.
And by the way do you like any other kpop groups? A.. and who's your bias from BTS?