A Lonely Person

"You will not stop her?"

Allen was surprised to see that it was this man of all people who directed the question at him. When he was doing his research on the people his fiancé knew, Shioka was the last person he would have thought to end up following her all the way here and to express such deep concern too.

"There is no need for me to do so. It is something she decided to do."

It's something she decided to do for herself. That's why he can't stop her. After the confrontation and talk with Kazuya. Allen realized that even if he tried to talk to her about the matter, he wouldn't be able to understand. Which is why he went to that place, he went back to that place and asked the one person he knew would have all the answers.