What is the meaning of a covenant (ʿahd) in Islam? And will God punish the disclosure of an immoral secret that resulted from a covenant to keep it confidential?

If a man entrusts you with a secret pertaining to an unlawful act that will occur in the future and harm others, then this secret must be divulged to the extent necessary to prevent the harm. However, if the secret pertains to an unlawful act that has already occurred and there is no necessity to disclose it, then it must be kept. The questioner must repent from her seclusion with this non-mahram man and her interaction with him, and resolve not to meet non-mahram men in the future.