Is it permissible to marry a repentant fornicating woman who feels remorse and aspires to chastity, and who went through difficult circumstances that compelled her to do so?

Adultery is a grave sin. Allah has associated it with polytheism and unlawful killing, as He says: "And those who do not invoke with Allah another deity or kill the soul which Allah has forbidden [to be killed], except by right, and do not commit unlawful sexual intercourse. And whoever does that will meet the consequences. The punishment will be doubled for him on the Day of Resurrection, and he will abide therein humiliated – Except for those who repent, believe and do righteous deeds; for them Allah will change their evil deeds into good ones. And ever is Allah Forgiving and Merciful." No circumstances justify adultery. It is not permissible for one who has fallen into it to contemplate suicide, for that is a greater sin than adultery. She must repent with sincere repentance and be certain of Allah's mercy, for Allah replaces the evil deeds of the repentant with good ones. There is no objection to marrying her if her repentance is genuine. It is unlawful for you to continue speaking with her, as that is one of the paths leading to adultery. Therefore, you must sever your relationship with her. If you wish to marry her, then contact her guardian for the lawful marriage contract.