From: Rabbi Moshe Sofer
To: Rabbi Lipman
A cantor's wife admitted to a forbidden act with another man and consistently maintained the admission, yet refused to accept a get. The Chasam Sofer rules that the beis din should not actively facilitate the divorce, but if the husband insists he may divorce her against her will only after formally accepting the Cherem of Rabbeinu Gershom—swearing his claim is sincere and not a pretext to pursue another woman. If the wife cannot be compelled, the husband is at minimum exempt from his support obligations.
Source: Shu"t Chasam Sofer EH II §109