In the tv show Ray Donovan why does Abby die in season 5?

In Season 5 of "Ray Donovan," Abby Donovan dies primarily due to her battle with cancer, which is a significant plotline throughout the season. Her illness exacerbates the already strained dynamics within her family, particularly with Ray. Abby's death serves as a pivotal moment in the series, impacting Ray and his relationships profoundly as he grApples with grief and loss.