What to do?

Lin Jing crossed his arms behind his back and kept staring at Su Wan, it was making him mad. Seriously, making him mad - his eyes couldn't help but dart towards her every now and then, yet she was hardly looking at him. He never believed that he was a complete dunce but now he did, his mind was blank and he couldn't think of one single idea that might earn him Su Wan's forgiveness. He had to restrain himself from walking close to her and twirling the loose strand of her hai, Su Wan's hair was shiny like that and it enticed him. Many times he had done that without knowing that he was doing it, it was like a subconscious act on his part, but right now he couldn't do that and that was making him annoyed.

Why can that pretty boy laugh and smile like that with her but he can't even talk to her without her snapping at him?

Because the pretty boy didn't make her mad, retorted his mind and just like that all of his steam blew out of his body.