Marcel was close to exploding when he thought Arianna was suggesting working in his club until he heard the rest of her words and the ravaging jealousy inside of him melted away. He couldn't even imagine the idea of Arianna working in his club where those lustful men could stare at her - his woman! The thought didn't sit right with him and thank the stars she didn't suggest that. It seems like she was beginning to understand his personality a bit.