By the 23rd century words such as 'gay' or 'straight' would be obsolete. People would just be people with lovers/partners/mates/spouses, regardless of sex or orientation.
As for crew gossiping, the fact the CO and XO were in a relationship would be something more shocking and cause for concern (due to conflict of interest), rather than them both being the same gender.
I don't see why some people have to make writing a same sex relationship such an important thing, its just the same as a heterosexual one except both parties involved have the same equipment. The emotions involved and intensity created are just the same between man/man or woman/woman as it is with man/woman. I have no problems developing an emotional and physical relationship between my male and female characters, so I don't see why other authors have to make such a big thing about it for homosexual ones.
Just my thoughts.
WhenI was reading fanfic on a regular basis (I don't anymore for a variety of reasons) I found the best slash-fics were not necessarily ones heavy on the sex but were the ones where the characters just happened to be gay and for the largest part their relationship played little to no part in the story. The writers tended to get the tone of the character and it was less about "OMG Kirk/Spock are gay!" and it was just a good Trek story first were the pairing happened to be same gender.