Jesus fuck....this manga...
Going from My Pet to this I really didn't expect to be feeling physically ill after reading the ending. NTR gutpunch did it's job once again, and Joy has been firmly placed at the very top of most disgusting manga character I've ever had the pleasure of reading.
However upon mulling over the story after finishing it I kinda take solace in a couple realizations.
First is that Natsu definitely was the one that Joy truly loved, or at least loved more out of the two. This mainly comes back to how Joy set up the whole triangle scenario. Natsu was the one she spoke to first, and the one she decided to deceive. I take that to mean that she was the one she really didn't want to lose, she was willing to gamble on Hye Yeon turning down her arrangement, but not Natsu. This view is reinforced in my mind by the ending. So I take solace in the fact that Joy will have to live with the fact that her actions caused pain to the one she truely loved, and hopefully has to deal with that pain for a loooooooooooong time.
Second is that once Natsu leaves the school, having been really popular, rumors are probably going to spread around about why exactly she left, which will probably turn her fans on Joy, making her school life considerably less pleasant. Fitting karma all around.
In the end, I really wish I had not read this manga. I don't feel I was left with a good story in the end, all I feel is physically ill when I think about the whole thing.