You and your best friend were similar alike.  But personality wise, you both were totally different.  Your best friend was the very popular type, mean at times, knows how to stand up for herself and others, etc.  While you on the other hand was somewhat shy but once someone breaks through your shell, you’re very open.  Your best friend was like the hero and you were just the unknown side kick.  You wanted to be like her since you both have ever met.  When you were little, you were bullied a lot and your best friend stood up for you.  She would even beat them up because she was also fed up with the bully’s attitude.  
Your best friend and her boyfriend met in middle school and now you’re all in high school.  Her boyfriend used to be a bully previously but now that he has met your best friend.  He changed for her.  You could tell why they were perfect for eachother.
Everything starts to change little by little.