Is it possible for a wife who confessed love to another person, and later regretted it, to have been insincere in her confession of love to that person, and for her love for her husband to be genuine despite that?

Expressing forbidden relationships as marital infidelity might lead one to understand that they are reprehensible because they are a betrayal of the husband, and not an act of disobedience to God. A husband's mistake does not justify a wife's forbidden relationships; she must either be patient or separate through divorce or khul'. If the wife repents with sincere repentance, there is no harm for the husband in keeping her. The husband, moreover, must protect his wife, close the doors of temptation for her, and prevent her from suspicious mingling with men.