Peace demands the most heroic labor and the most difficult sacrifice. It demands greater heroism than war. It demands greater fidelity to the truth and a much more perfect purity of conscience.
Fidelity is a term that refers to faithfulness, and this is expected between a husband and wife because it is mentioned in the wedding vows taken. If you show fidelity then you are showing loyalty towards this person. Infidelity can destroy relationships and marriages, because it is a betrayal of trust and loyalty and it can be devastating for the person who is betrayed.