Women who convert to Islam for their husband/fiance?

You can't revert for a man or a woman. You have to do it for yourself, and as you know in Islam everything is about your intention. If she is simply doing it to make her husband happy, its not going to mean anything. She has to truly believe it herself, and Islam is not something to take lightly or do on a whim. Insha'Allah she will be guided to the straight path. Just keep making dua for her and be there to answer all of her questions to the best of your ability.