The main reason why you can’t have intercourse during menstruation is because of the following reasons: 1. When menstruation occurs, the inner opening of the cervix is basically closed during normal times and is in a relatively relaxed state when menstruation occurs, so that menstrual blood can flow out. The actual fact is that you can find a lot of people who are not able to get a good deal on a lot of things. Some women think that menstruation is a normal physiological phenomenon and they can have normal intercourse, but they are very wrong, they must protect themselves and spend their menstrual period safely.