The matters of the Han Kingdom were settled and the Duanmu Family was taken care of, so there was no reason for Lin Fan and Duanmu Ming Xue to stay any longer.
They had stayed long enough for Duanmu Ming Xue to catch up with Duanmu Chao, so there was nothing left for them to catch up with.
Though Duanmu Chao wanted Duanmu Ming Xue to bring Duanmu Yi back to the Duanmu Family and live with them, he knew that she didn't want this. He knew that with the relationship between Duanmu Ming Xue and Lin Fan, she would want to be with him.
So he didn't stop her in the end.
But he still said, "If you ever need anything, you can always come to us. We'll always be your family."
In the future, it seemed that there was another place for them if anything ever happened to them.
With that settled, they headed back to the Mu Empire on the back of Igneel.