Gwendolen Harleth is beautiful and wilful, desired by many men, a fact which she revels in.
She is sorely disabused of that notion, when she learns that beauty and charm alone are not enough to gain her followers on the stage— it requires years of training and hard work.
Glasher had previously left her husband for Grandcourt, and had also been given promises of marriage, but he has never kept his word.
Grandcourt had recently made a new will, in which he left the majority of his fortune and estates to his son by Mrs. Glasher, if his marriage to Gwendolen did not produce a male heir.
He created the new will specifically in an effort to coerce Gwendolen to do her wifely duty with him to produce a legitimate and male heir.