Is it permissible for a girl who willingly committed adultery not to inform her future husband about it, taking into account that not informing him is considered deceit and fraud?

Concealing past fornication is not considered deception or fraud; rather, it is a concealment commanded by the Sharia, due to the benefits it achieves, the harms it averts, and the honor it safeguards. This is based on the Prophet's (peace be upon him) saying: "Avoid these abominations… and whoever commits any of them, let him conceal it with Allah's concealment." An exception to this is if the husband stipulated virginity; in this case, concealment would be deception. Here, the woman must repent and keep the matter concealed. If the husband discovers the matter, she may use ambiguous statements and equivocation to make him believe it happened for a normal reason. The woman who fornicated must make sincere repentance and perform many good deeds, for Allah Almighty said: {Indeed, good deeds do away with ill deeds} (Hud 11:114), and the Prophet (peace be upon him) said: "Follow up a bad deed with a good deed, it will erase it," and "Charity given secretly extinguishes the Lord's wrath." She must also stay away from the causes of indecency and temptation and keep her matter concealed.