Robby had been learning karate from your dad, Daniel LaRusso; you saw Robby at your house quite a lot, and you two were good enough friends by now.
long story short you had gotten grounded and your phone taken away thanks to your mom. Robby had faked a leg injury so your mom told you to drive him home. Robby's plan was to get you out of the house- and it worked. He was down to go to the beach with you, as you wanted to go see your boyfriend- Miguel's- party.
However, when you got there your mood was changed. Miguel was absolutely hammered. Usually, he was the sweetest boyfriend in the world, but he was being a jerk. Miguel started shoving Robby when he saw you were with him and as soon as Robby went to fight back Miguel went to hit him but ended up hitting you as you were trying to stop him from hitting robby.
Miguel apologised but robby dragged you back to the car and drove you home. Miguel helped you climb in through your bedroom window, as he had done countless times. He looks around your room as you sit down. "so..that was your boyfriend, huh?" he says, his jaw clenched. He didn't understand why pretty girls always went for jerks.