Because the Stenia and Thesmophoria were historical examples of woman-only festivals, it is logical to think that there was probably an equivalent festival (or festivals) for the men that have not made it into the historical record. In the modern day, we possibly need to consider making single gender festivals again for SOME of the festivals because of the mythology behind them. The Stenia and Thesmophoria both commemorate Demeter grieving for Persephone and the reason behind them being women only may have been because women would not have done certain activities around the men of the household because of relatively strict segregation of gender roles at the time.
What does this mean in modern terms however? Well, today is a day for frank discussions of sexuality and perhaps even a dirty joke or two. I don’t think the Two Goddesses of Eleusis would mind…..