He is near

"How did he know"

    After class ends I call my mom to pick me up. As I am walking towards the front entrance of the school I see that girl that looked a little strange from earlier. She looks at me and gives me a "remember what I said" look.
I nod and walk out of the school and I sit on the bench and wait for my mom. While I'm waiting I see this guy and he keeps staring at me so I go and talk to him. "Hey I saw you staring at me so I thought that you needed something." "No I just think your so pretty." "Oh well sorry but I don't like you." "Is it because you have a boyfriend." Then my moms car pulls up "umm I'm not going to ask so I got to go, my mom is here so bye." I wave bye and get in my moms car. How did he know I have a boyfriend, I have never told anyone that I have a boyfriend.