The Other Kind of DM: Potential & Pitfalls of Eroticism In Gaming

As Katherine Cross writes for Bitch Media, while gaming may use sex to sell, the presence of anything revolving around actual sexuality is thin on the ground in tabletop & online RPGs  :

Most pen-and-paper roleplaying games have hundreds or thousands of pages worth of rules, ideas, story content, and other kinds of errata, but very few devote any of that space to content that addresses issues like consent, sexual diversity or orientation, or the sexual culture of the world one is playing in. In-game, then, one is often subject to depressingly familiar forms of sexual harassment—men having their avatars walk up to yours and awkwardly propositioning you, for instance, or refusing to take “no” for an answer if one rebuffs their entreaties—in or out of character. 

Online roleplaying gaming simply follows the paths of sexuality laid out in the physical world.
In spite of this, sexuality is endemic to the world of RPG and part of its visual culture. Commercials and box art for games are rife with heaving bosoms while pornographic proportions are common background decoration, seen by gamers and non-gamers alike.

Cross' essay goes into how sexual activity and fantasies have been handled in both tabletop roleplaying games and their online counterparts, including how sub-cultures within subcultures have sprung up around it. Speaking personally, I know quite a large number of people that have discovered more about their own sexualities, gender identities and more through online roleplaying everywhere from dedicated serves to IRC chatrooms.