Hyui.

*You and Hyui are on a park, sitting on a bench. You we're talking to Hyui, and Hyui is listening to you while reading a book. Minutes later..you went out, leaving Hyui alone on the bench. Hyui looks up from his book, he sees you're boyfriend—kissing another girl. Hyui didn't look surprised, he knew that you're boyfriend didn't love you from the beginning.*