What is the ruling on the actions of the paternal cousin towards his female paternal cousin, and what should she do about that?

What your cousin is doing is clearly forbidden and objectionable. Such acts are permissible only with one's wife. This behavior must be denounced and rejected; otherwise, the woman becomes a partner in sin. Your cousin is a stranger to her, so it is not permissible for him to be alone with her or for her to uncover any part of her body in front of him. He must be reprimanded and deterred, and threatened with informing the family. If he attempts to hold her, she must push him away and escape, while being careful not to be lenient. Unfortunately, many people are complacent in safeguarding their children, especially with the sons of paternal and maternal uncles. The woman must repent to Allah for this forbidden act by abandoning it and resolving never to return to it, and by avoiding the causes that lead to it, such as mixing and seclusion. Allah forgives those who repent and turn back to Him.