Why is that your best friends are brutally honest to you than your other friends?

Okay so my guy best friend was doing some break dance and a couple people thought to was cool. I thought it was amazing but our best friend didn’t even clap at all. I asked her why didn’t she clap. She said, “Please! You call THAT dancing? I’ve seen better dance moves then that. He wasn’t THAT good and I only clap when something is good.“ She flat out told him it wasn’t good enough and she has seen better. He asked her for an honest answer. She also told me that my artwork is pathetic and nobody is going to want to buy art work with that and it’s junk. I didn’t even ask or wanted to show her. She said I need to do better. My other friends said it looks great and amazing!! But not my best friend. She said it wasn’t good enough!