Does lying to the fiancée during the engagement affect the validity of the marriage contract, and does a husband's infidelity invalidate the marriage contract if he had told his fiancée during the engagement what implies his distance from such sins?

Lying to the fiancée does not invalidate a valid marriage contract. However, if the husband conceals a defect that prevents intercourse or conceals repulsive diseases, the wife has the right to annul the marriage.

Lying is forbidden and considered deception. If a man informed his wife before marriage that he abstains from indecencies, but then violated this, it has no effect on the sanctity of the marital bond.

It is obligatory for whoever falls into indecency to repent to Allah by abandoning the sin, regretting it, and resolving not to return to it, while concealing oneself.

Describing illicit relationships as merely a betrayal of the wife is a concept contrary to Islamic law.