Actually the fraternization rules are more about command than sex.
Think about it in terms of the business world. If the boss is dating a secretary it matters not a whit how good she is at her job. If she gets a raise or a promotion is is seen as not earned. That is the issue with fraternization.

Quote Originally Posted by MMI View Post
It seems to me that any form of sexual activity in the military is seen as a distraction - hence the "no fraternising" rule for straight relationships, and no rule for gays because "there aren't any queers here". The no fraternising rule wasn't necessary before women were allowed in the forces, either, so when gays are permitted to be open about their sexuality, as they surely will before long, they, too, will be required not to fraternise.