Why did Nephthys had an affair with Osiris?

Nephthys had an affair with Osiris primarily because she was drawn to his qualities as a god of fertility and regeneration, contrasting with her own role as a goddess of death and darkness. The affair led to the birth of Anubis, the god associated with mummification and the afterlife. This union illustrates the complex relationships among the Egyptian deities and highlights themes of duality and balance within their mythology. Additionally, the affair serves to deepen the narrative of Osiris's eventual death and resurrection, which is central to Egyptian beliefs about the afterlife.