Jung HaeIn's unrequited love letter to Somi on ”Mr. Perfect Next Door” is revealed!?

*Contains synopsis and spoilers. Jung HaeIn, whose true feelings were revealed, made the excuse that it was just a prank.
In episode 6 of the tvN Saturday and Sunday TV series "Mr. Perfect Next Door," which aired on the night of the 1st, Song-nyeong
The appearance of Seunghyo (Jung HaeIn) having his letter discovered by Somi was broadcast. Seon-nyeo went to Seunghyo's house on an errand and found the time capsule that Seunghyo had hidden while he was away.
He searched for the letter in the cell. It contained Seunghyo's true feelings towards Songnyeong as a high school student. When Seunghyo found out that Songnyeong had read the letter, he snatched it away.
"I'm sorry. I didn't mean to read it secretly. I was upset that you were the only one who saw my letter," Sun-nyeo apologized, crumpling up the letter and throwing it away.
Seeing Seunghyo throwing it away, she was surprised and asked, "Why did you throw it away?" Seunghyo replied, "You saw it, it was a prank. I think I was trying to make fun of you for real at the time.
"I saw you playing a prank on me," he said. Sunnyeon said, "Right? It was a prank, right? I was surprised," laughing awkwardly, and Seunghyo replied, "I thought it was funny, but it wasn't that funny.
"I didn't have any," he said, his expression hardening. After returning home, Song-nyoo thought carefully about the letter, "What was that letter? Really?" and said, "Is this prank economic development? You said you planned it for 10 years? But if it's not, it's not.
So why crumple it up and throw it away again?" I thought, feeling annoyed.