is it a sin to think about your husband sexually

No, it is not a sin to think about your husband sexually. When you think about your husband, it is perfectly normal to have sexual fantasies and欲望. This is a natural part of human psychology and physiology. However, it is important to remember that these fantasies and欲望 should not infringe upon your marriage关系 or cause harm or distress to your spouse.
It is also important to note that your husband has a fundamental human right to privacy and autonomy in his own life, including his sexual thoughts and desires. While you have an interest in your husband's desires, it is crucial to respect his independence and not to force or manipulate him into satisfying your own欲望.
Finally, it is important to seek professional advice and support if you are struggling with sexual fantasies or欲望, or if you are concerned about your husband's mental or emotional health. A therapist or sexologist can help you navigate this issue and provide guidance on how to address your concerns in a healthy and supportive way.