How did we fall in love?

Why would she do this ?

*Jins pov*
I began to get ready for another day of school I can't wait to see Y/N today. I think I should make my move to make her mine . I arrived at school and saw Y/N  with her friends I went up to her and greeted her . "Hey Y/N. " I hugged her tightly . "Hey Jin I just wanted to say that I had an amazing time with you  yesterday ." Y/N said. " Me too we should go to the park more often it's so beautiful to see the sunset and the roses." I blushed. I really wanted to say that Y/N is beautiful that I love to see her everyday . Y/N and I were walking to class , but we saw Jessica in the hallway. "You may think that you won that fight we had but I guaranteed you will not win the next." Jessica said to Y/N. "Oh please you think that , that was a bad beating you got believe me when I say this the next beating will be to the point where you will never speak or look at me again." Y/N  threaten Jessica. I pulled Y/N back a little bit cause she was getting close to Jessica.
Jessica just walked away while laughing . Y/N and I went to class and finished our project . It was lunch time and I notice Y/N wasn't there .I know something's wrong I saw Y/N friend and asked her where is Y/N she didn't know . I walked out of the lunch room I walked by the custodian room I heard movement going on . I decided to open the door and my jaw dropped as soon as I did my heart was breaking I saw Y/N and  Suga in there together Y/Ns hair looked messy and her lipstick was smeared I looked at Suga his hair was messy and he had lipstick on his lips . I was so hurt I felt a tear go down my face I know Y/N  and I weren't together ,but I have strong feelings towards her . Y/N wanted to explain but I didn't want to hear it I left the school ran as fast as I could to get home . It was around 5:00pm school was out for the day I instantly heard my phone go off I knew it was Y/N  I ignored her I couldn't talk to her after what I saw .
Y/N : Hey
Y/N : Jin I need to talk to you it's important please
Y/N : Please Jin it's not what you think . Nothing happen.. look I'm just gonna come out and say it I have real deep feelings for you Jin I've fell for you and I don't know  how . 
Y/N : I'm sorry for what you say just let me explain to you what happened please I bet you .
At this point I didn't believe a word what Y/N said I was still hurt  .
Y/N : Okay I'm gonna give you your space , I just hope you give me a chance to explain what happened when you are ready to give me a chance to explain please come up to me . You are the only person that gets me and you are the only person that I can be myself.  Goodnight princecharmanderjin
Should I give her a chance to explain?  Even if I do she won't tell the truth I thought she was different.  Why me ? Why her ? Why did I have to catch feelings so quickly ? Is she the one ? But after what I saw my biggests question is why would she do this ?