Hi!! I don't think that you should worry about sharing bgm with other games, I've seen games share bgm and background images and it never bothers me! (Which I totally understand because drawing backgrounds is something I always avoid -u-") If the music is appropriate for the scene then have feel free to use it :)
I haven't watching k-dramas in so long, but I enjoyed Prison Playbook! It's definitely more of a drama than a romance one and it was pretty long, but it's one of favorite stories I've ever watched in a show :) I really should rewatch it ^-^
I hope you're getting enough rest with all this productivity! Have a good day! ^u^