How does Will Ladislaw’s friendship with Dorothea Brooke affect her marriage?

Will Ladislaw's friendship with Dorothea Brooke significantly impacts her marriage to Edward Casaubon. Casaubon, a pedantic scholar, becomes jealous of Dorothea's connection with Ladislaw, who is described as a young, headstrong idealist and Casaubon's cousin. This jealousy leads Casaubon to forbid Ladislaw from visiting Dorothea, even as he is dying.12

After Casaubon's death, Dorothea discovers his will stipulates she will be disinherited if she marries Ladislaw. Despite this threat and the potential for scandal, Dorothea and Ladislaw fall in love and ultimately marry. This union represents a departure from her disastrous first marriage, where her idealism led her to marry Casaubon with the hope of assisting his work, only to find him ineffectual and controlling.23