"This letter will ruin everything" Yerin said to herself

Even though she knows that it will somehow break her chances with Sinb and it would be easier to just to destroy the letter instead, she cant still make herself do that.

Why? 

      Because Sowon has done nothing but just good to her and she isnt that bad just blinded by her love for Sinb. So she just decided to hide it out of everyone's reach.

     Then Yerin write a letter as a replacement to Sowon's letter making it seems that she is the one sending those letters to Sinb.

   So the one Sinb had read was Yerin's letter and not Sowon's..

     Dear Sinb, 

           You have known me as a very straightforward person. I always show how much you mean to me to the point that im even willing to disturb the class. Sorry if it makes you uncomfortable. I never show this side of me to anyone but because its for you im happy. Those letters all shows how much you mean to me. I hope you can give me a chance because I love you so much..

                                                 its me, 

                                                   JUNG YERIN

       After Sinb have read the letter, she immediately looks for Yerin to confirm something. After few minutes of roaming the school she finally found Yerin. Yerin is with Sowon and their other classmates.

       Sinb immediately run towards them.

SinB!! Sowon happily c