"Out of all places, why did you bring me here?" Mary asked.
The place that she and Arion are in right now is the place that they both treasure. It's the place where Arion proposed to her, and it is also the place where she goes whenever she misses Arion after his disappearance.
Now that Arion is right by her side, Mary doesn't know what she should feel right now. Should she feel happy? Angry? Or upset? She wants to express her emotions to him, but she doesn't want him to know that she is happy to have him back.
"I chose this place because this is the only place I can think of for us to talk freely without care for others." Since the place is rarely visited by other people, and at this time around, no other people besides them are coming.