After deciding to worship yusuf's god, zulaikha's life turned around. She managed to catch a glimpse of yusuf, meet him, have her beauty and youth returned, and ended up with the man of her dreams. However, her true turning point in this is when her looks are returned.
Were they really returned to her? Did yusuf posses this divine ability to produce what time had taken away from her? While Yusuf was affiliated to the divine, besides his dreams, he never really performed any physical miracles. I would like to question whether or not Zulaikha's looks were truly returned.
Could it be interpreted that she only wished to be beautiful in Yusuf's eyes? Or that she was beautiful in his eyes again, so that she could be with him? It is possible that because of her change in spirituality, yusuf found her more beautiful, or that in his words of prayer, he welcomed her into the religion and therefore was perceived as more beautiful. This would also explain why the angel Gabriel told Yusuf that he could finally marry her.