“As a friend of the girlfriend’s, you should share what you know. Yet your role as a confidant means you agreed to keep your friend’s secret quiet. If they thought you would share it with their girlfriend, they probably would not have told you that they were cheating. In this situation, obligation gives us no decisive answer about what you should do.”  

“As a friend of the girlfriend’s, you should share what you know. Yet your role as a confidant means you agreed to keep your friend’s secret quiet. If they thought you would share it with their girlfriend, they probably would not have told you that they were cheating. In this situation, obligation gives us no decisive answer about what you should do.”