Tae-sung being related already takes him out of the running of being a possible love interest... regardless of his feeling they r blood related and this would be very weird, if they would've ended up together. him being such a tragic character was freaking depressing...

But the major fact is i don't get why they r so infatuated with her. it's not that i'm saying - she ugly, but in order to be thunder-struck the sec u see someone, there should be something special about them, and she is just another girl. what's more, the more we get into the movie the stupider she gets (sorry, but that is a fact) that so called friend calling her - just to show her that she is now dating the guy she had a crush on. that not enough to wake u up to the fact that she aint ur friend? u keep taking her calls and meeting up with her? why?!? unless u love being stepped on ¯\_(ツ)_/¯
then there is that encounter with the bo girl, after understanding she was set up by their "friend" she stands there getting beat, saying she won't forgive them and crying. that not Stupid?!? not to mention that scene in the field where u got cops after ur ass and she standing the bawling her eyes out...

i hate female leads that don't have a backbone, don't need to be kick-ass, but u have to show growth and have to stop being a pushover... otherwise what's there to root for? meeh