Why do you suppose Chillingworth's marriage failed? What serious consequences did the failure help to bring about for Hester?

Well, Chillingworth is an old man and a socio-path. That's probably the first red flag. Hester is young, caring, full of life and beautiful. There is our second problem! Finally it is revealed that Hester really didn't want to marry the guy in the first place. Hester basically had to flee Amsterdam for the freezing Puritanical hell of Boston.

Hester and her husband come face to face for the first time when he is called to her prison cell to provide medical assistance. Chillingworth has promised the jailer that he can make Hester more “amenable to just authority,” and he now offers her a cup of medicine. Hester knows his true identity—his gaze makes her shudder—and she initially refuses to drink his potion. She thinks that Chillingworth might be poisoning her, but he assures her that he wants her to live so that he can have his revenge. In the candid conversation that follows, he chastises himself for thinking that he, a misshapen bookworm, could keep a beautiful wife like Hester happy. He urges her to reveal the identity of her lover, telling her that he will surely detect signs of sympathy that will lead him to the guilty party. When she refuses to tell her secret, he makes her promise that she will not reveal to anyone his own identity either. His demoniacal grin and obvious delight at her current tribulations lead Hester to burst out the speculation that he may be the “Black Man”—the Devil in disguise—come to lure her into a pact and damn her soul. Chillingworth replies that it is not the well-being of her soul that his presence jeopardizes, implying that he plans to seek out her unknown lover. He clearly has revenge on his mind.