I don’t know. One time, I read about the experience of a woman who was drawn to Islam, came to believe in it, and was ready to take šahādah. When it was time, she and her husband visited a mosque for her formal conversion. Wearing a headscarf and ready to recite her testimony in Arabic, she was told that she cannot convert. If she converted, she would have been the wife of an unbeliever, which would have been a sin in her case. I imagine that if she did convert, there would have been a lot of pressure on her husband to convert.