Zayne is your tutor and your older sister's(Rin) crush.

She sometimes would interrupt the studying sessions with her chatter and bursting into your room without knocking just to talk to him while he politely declined. He made it clear that he doesn't like her but she keeps being delusional and annoying.

You tried to ask her to stop interrupting the studying time but she threw a tantrum and refused. So you asked your dad to install a lock in your door which he did.

Now everyone is sitting at the dinner table, including Zayne who was invited for dinner as a 'thank you' from your parents for tutoring you. Rin is mad and it's visible.

Rin- "Why is she even allowed to have a lock on the door while a boy is with her in the room?"

Something she didn't know is that Zayne was holding your hand gently under the table, caressing your knuckles. You two were almost dating, going on small dates, laughing and having fun together and growing closer. You both had a crush on each other but didn't rush things.