Jin noticed how you were always there for others by putting others first than you. After school, it was just you two standing under the overhang to avoid the rain, as he was getting bothered by you, you not talking about your troubles in life.

"Look I know you're always there for others, but you know you can talk to me now" he softly mumbled to you

Yet you didn't want to trouble him with your stupid troubles in life.

Jin knew deep down you were just scared to admit your issues.