I’m not a guy so I can’t say with any certainty, but my spitball theory for why many men are skittish about period sex is because of the unknown energy and possibilities that are held within the blood a woman sheds each month. Primal and often taboo, menstrual blood and associated pain / PMS is a variation on normal and not something a man can solve or fix. He can’t help a woman get through it faster or make the blood less. A woman’s cycle is not to be fixed, it is to be honored.
It’s a space to give space and listen. A time to honor a woman’s body for the shedding of a potential life it did not get to grow. It is a time for creativity and reflection on the power we hold. Regardless, if a woman has zero desire or an absolute passion to bear children, a woman’s cycle is a monthly reminder of her design to bear life. That design is the power of a mystery she can channel into so many variations. That mystery of creation is a topic that has been so deeply hidden that many women don’t understand it, fear it, and feel shame around their menstrual blood. For the women who have come to a place, to be in connection with their feminine power, her menstrual blood is nothing to fear, but a mystery to celebrate. That awareness is a rare and beautiful power.
For a man to be ok with, even embrace, sex with a woman moving through her period- to not mind being marked for a time, cleaning together, or falling asleep amongst sheets that hold the smell that is theirs- says he is able to share a deep vulnerability with a woman. For a man to accept the untamed beauty of a woman during the days she bleeds, to share her body and hold her in such a complete form of primal acceptance is to say he honors and accepts her fully as a woman.