I think that the issue with regard to relationships is that in any military unit, you cannot have Sgt Ambrose not ordering Pvt Berlios to attack that hill, just because the two if them have been fucking like rabbits every night. If Pvt Berlois is the one to go then go he must, and if he gets killed then Sgt Ambrose must pull his act together and get over it!<br/><br/>This is why women have been excluded from front-line combat duty and gays in the worlds armed forces were seriously frowned upon, until recently.<br/><br/>However, I think by the time we get to the 24th century even the most backward nation in the world when it comes to sexuallity will have grown up and realised that sex has its rightful place. Sexual relationships aboard star fleet vessels are quite common - It was always implied that Kirk had a relationship with Yeoman Janice... Ryker and Diana Troy, Picard and Beverly Crusher, Tasha Yar and Data.... And of course there was Kira Nerise and Odo, Worf and Jadzia Dax, although those last two couples were on DS9, but they were also crew members of the USS Defiant.