Your families are close, so they left him over at your house while your parents go on a trip.

He was in your room, on your bed, while you were in the bathroom changing into your pj‘s

You left your phone on the bed, and he saw a notification from snap, a guy.

he instantly took your phone and snapped the guy back: „Dude, she‘s mine“

he was mad that a guy tried to flirt with you