After attending Amazon Lily's celebration banquet, nominally held to celebrate the "lifting of the curse" but actually a thank-you feast Boa Hancock had prepared for the cats, Xie Wen planned to leave the next day.
After all, while Ai Haibara Meow and Meowrah had been figuring out how to remove the Celestial Dragon Hoof Mark, Robin had finished her archaeological work, and the cats had finished exploring. There really was no need to stay on the island...
Of course, if they really wanted to stay a few more days, they could find a reason.
Ai Haibara Meow had been busy removing the marks all this time. Although she had asked the other cats and the Kuja to help gather medicinal ingredients, she had made absolutely no progress in her research into why only girls were born on this island.
But Ai Haibara Meow already had a whole pile of research projects on her hands. A matter with so little bearing on them, like why only women were born on Amazon Lily, was not important enough to make all the other Research Commission members stay to keep her company.
Besides, their Research Commission was now allied with Amazon Lily, and the Dudu had some of the best mobility in this world. Ai Haibara Meow could easily come back to research it when she had time later.
Yes, it absolutely wasn't because a certain Sapphire Star had been scared off by the island's "enthusiastic" women and wanted to make a quick getaway.
Absolutely not!
When Boa Hancock and her two younger sisters heard that the cats were leaving, they naturally hated to see them go. But the cats-read: the Sapphire Star-had made up their minds, and even the most beautiful woman in the One Piece world could not persuade them to stay.