Everything involved Arthur in their world. It would always be a complete circle between them. While she explained herself he felt like he was watching from up above. Everything she had asked of him he had done without putting her in jeopardy, and when he could not hold it from Arthur any longer he gave her the heads up. He knew giving Arthur the open door could lead to this. He'd thought on it for weeks.
It should have been no surprise that she had seen Arthur. He knew in his heart she wouldn't be able to resist. It didn't mean it hurt any less.
"What does that mean for you now?" He didn't want to say "us" just yet.