Symptoms of the BFF effect:

• A racing heart when around the best friend.
• Burning jealousy when the best friend flirts with someone of the opposite gender
• A sense of contentment when the best friend spends time with you
• Wishing for your friendship to turn into something more
• A need to run to the best friend's house when something happens
• When the best friend becomes someone you can't stop texting, calling or thinking about
• When you find out that you are in love with the best friend

If you have any one of these symptoms, you might have the BFF effect. 

But that's okay. Then you and I are two peas in a pod. Because I am in love with Oh Sehun.