Betrayal, especially of a moral obligation
Don't you start that infidelity stuff on me.
Maybe Darian hadn't been talking about infidelity but about something else.
His infidelity to his wife and his harshness towards his son Carlino are blemishes on a splendid career, but he more than expiated these faults by his tragic end.
Dio Cassius and Capitolinus charge Faustina with the most shameless infidelity to her husband, who is even blamed for not paying heed to her crimes.
Napoleon on the other hand spoke of her in his will with marked tenderness, and both excused and forgave her infidelity to him.