Just as he predicted, Maria got the moonwalk-esque movement pretty quickly. She wasn't as fluid as he was yet, but that took time.
Rather than offer advice, Dorian ceased all dancing when her face and her mood visibly fell. Maybe solitude had not been a very good topic at all. He ached that he made her remember such pains.
Nervously, he held out his arms around her as to indicate he wanted to hug her, maybe even comfort her. It was good to relate on some things, but there were some instances where he wished no one could ever relate to his suffering. No decent person would wish loneliness on another.