Cyberspace can also be a great place to carry on an illicit relationship.
In Paulina Borsook's short story "Love Over the Wires," (Endnote #26) the heroine carries on a torrid epistolary affair with one man while living with
another. She can be sitting at her computer writing to her lover, while
her official significant other is in the next room.
There are plenty of "adults-only" discussion groups and chat rooms,
intended for sex talk rather than romance. And MUDs involve some
proportion of sexual activity.
For the most part, romance Netiquette is the same as romance etiquette.
Here are a few questions you might ask, however: