Rosalie had just recovered. After what happened, Byron was worried about letting her stay outside alone.

“You can go back first. I want to hang out with Mary for a while.”

Rosalie could see Mary had something she wanted to tell her. Thus, she decided to go along with Mary's plans.

Byron frowned, and he looked worried.

Mary understood his worries and said, “If you're worried, you can send someone to protect us. You don’t have to worry about me making Rosalie do something that'll betray you.”