Aharon considers the mission, and therefore initiates the sending away. The second chapter begins in Parashat Yitro. The Children of Israel underwent a process of consolidation. Tsippora missed all this. Now she desires to join, brought by her father, who returns her to her husband's tent.
Moshe is already in higher spheres.
If he did indeed return to his divorced wife, it was only temporarily, until he pitched his tent outside the camp. We are faced with years of silence. This is her appellation and this is her memory. There is a school of commentary which seeks to show that she was pleasant and her deeds were pleasant, yet despite this, Moshe distanced himself from her. Some commentators attempt to construct gematriyot which compliment and beautify the Cushite.