Is there any sin on a wife who was divorced because of her insistence on completing her studies, which were previously agreed upon with her husband, knowing that he does not pray and threatens divorce for disobedience?

So long as the wife has not requested a divorce, there is no sin upon her. However, her defiance of her husband by abandoning her studies, which distract her from his rights, is not permissible, and she would be sinful for it, unless she had stipulated that to him in the marriage contract. And if the husband does not pray, then separation from him is better.