In Islam, fornication and adultery are grave sins and committing either bears serious consequences in this world and the hereafter. However, in a practical and matchless approach to prevent the crime of zina before its occurrence, Islam does not merely forbid the actual deeds, but Islam also declares each and every circumstance or avenue that may lead to fornication and adultery as forbidden. Allah Almighty says, “And come not near unto adultery. Lo! it is an abomination and an evil way.” (Al-Isra’: 32)
But those who commit this sin should not lose hope in Allah’s forgiveness as long as they repent and are determined to correct their lewd conduct.

A man and a woman, who committed Zina, should first of all repent and seek Allah’s forgiveness. As for the issue of marriage, it is permissible for them to get married to cover their sin and to help each other lead a righteous life.

In fact, Islam encourages them to get united in marriage to have a lawful relationship particularly if their relationship results in pregnancy.
The Egyptian Darul Ifta’ (House of Fatwa) states that: “It is unanimously agreed that an adulterer/or fornicator is allowed to marry the adulteress/or the fornicatrix he impregnated. The wisdom behind that is to secure a Muslim’s best interest and attempt to preserve the woman’s honor.”

Speaking about the permissibility of marrying the woman with whom one committed Zina, Sheikh `Abdel-Khaliq Hasan Ash-Shareef, the prominent Muslim scholar and Da`iyah, states the following: “I earnestly advise that man to marry the woman with whom he committed Zina. This is the first step to atone for the grave sin he committed. In addition, both the man and the woman (if she is a Muslim) should sincerely repent to Allah and seek His Forgiveness. According to the Shafi`es, the best solution for the one who committed adultery with a woman is to marry her.

Thus, I earnestly advise the man to repent, marry the woman, take care of the child, fear Allah and to be honest and to promise Allah not to harbor ill intentions towards the woman. He should keep in mind that Allah will judge him according to his intention.”

Having clarified the above, there is nothing in the sources of Shari`ah telling that marrying such a woman will bring trouble for 7 generations. But once they have sincerely repented their sin and got married, Almighty Allah promised to forgives sins of those who after doing sins indulged in repentance and asked Allah for forgiveness. The Prophet (peace and blessings be upon him) is reported to have said, “One who sincerely repents of his sin is as if he had never committed it. When Allah loves one of His servants, his sins do not harm him. Then he recited the verse: ‘Assuredly, Allah loves the oft-repentant and those who always seek to purify themselves.’” So, after their repentance and getting married, there is nothing to the effect that their marriage will bring trouble for the family.