There are some yes, Just check on a few directories that malcolm1 runs here. He accepts adult/sexual stuff.
You can submit the site to the following: http://www.directorypro.biz/Society/Sexuality/ http://www.mishre.com/Health_Fitness/Sexuality/ http://www.emporium-directory.com/Society_Culture/Sexuality/
I would accept sites on sexuality, as long as its not pornographic, gay, lesbian related sites etc have their place. If its sexual discussion, possibly sexual health or something? thats fine by me.