From: Rabbi Moshe Sofer
To: Rabbi Meir Pal
The Chasam Sofer rules that a husband who belatedly accused his modest wife of adultery amid financial quarrels and personal hostility is not believed, as both the Maharik's and Rashba's leniencies apply. The wife retains her full kesubah and the husband cannot compel divorce; if he persists in forcing a divorce without substantiation, he faces excommunication for circumventing the Cherem of Rabbeinu Gershom.
Source: Shu"t Chasam Sofer EH II §106