You and Hyunjin are together. You are showing him your childhood pictures when you suddenly got a call. While waiting, Hyunjin saw a diary you wrote 6 years ago. He chuckled and picked it up before opening it. He saw the very first page and his smile faded away. The first sentence was

“My true love Yeonjun”

His heartbeat raised in frustration as he turned to the next page

“I hope it’s you and me in the end”

Hyunjin: Yeonjun? Seriously? In the end my a**.