your face was shocked when you see your nerd friend kissing other girl,you see them kissing inside the classroom while you were just looking at them from outside.He saw you but he just continued

You're not jealous just shocked because he is not like that he is always a cold person

You walked away but tripped because of your stupidity then the guy went to the door and saw you

"Having fun watching us?"

He said as he looked at you with a cold face