Is it Islamically permissible for a fiancée who had a previous relationship to marry her fiancé, who swore, "You are forbidden to me if you had a relationship before me," after she had informed him that she had no prior relationships, given that the marriage is imminent?

The suitor was wrong to ask about your past, as this violates Islamic law because it involves revealing what has been concealed. Islamic law commands concealment for anyone who has committed a sin. Therefore, you were right not to inform him of what occurred, but without outright lying, by evading or hinting.

You must repent and feel remorse. Your description of the old relationship as "not embarrassing" is incorrect, for every unlawful relationship between a man and a woman who are not spouses should be a source of embarrassment.

As for his statement: "You are forbidden to me," as long as he has not contracted marriage with you, no prohibition takes effect after marriage, because there is no divorce before marriage, and a woman does not become one of his wives until after the marriage contract.

The fiancée is a stranger to the suitor until the marriage contract is concluded. Therefore, it is not permissible for him to be in seclusion with her, touch her, or speak with her merely for enjoyment. Rather, speech should be for a need and a legitimate benefit recognized by Islamic law, and within the bounds of modesty and seriousness.