If Bi is OK, then Dirisha Zuri from Matadora, who is also in many of the other books set in that universe. She’s in a ménage à trois with a man and another woman, and also bonds with her long term female lover Geneva.
If videogames count, by the time you get to Mass Effect 3, your (male or female) Commander Shepard can be straight, gay/lesbian, bi, or even a xenophile (pair-ups with opposite gender aliens or with a female-shaped non-gendered alien).
Not a main character, but an important one: Admiral Cain from Battlestar Galactica.
That’s nuttin’! Find a three-sexed species and go every which way! 
Xena? But maybe that’s just where I land in the debate.
If dark fantasy is acceptable: the main character is gay in Sacrament by Clive Barker and one of the most important secondary charcters in the Mortal Instruments series by Cassandra Clare is as well.
There’s a debate?
Yes, there have been a lot of gay characters in Clive Barker. And some in his fiction, too.
Been a while since I read it, but I recall the protagonist having multiple homosexual encounters, not just one.
The lead character in The 97th Step likewise has a long-term sexual relationship with another guy before settling down with one woman after another.
It’s possible…it’s been probably ten years or more since I read the series. I just recall that episode the best because it was skeevy with the underage boys.
Well, I guess all the groundswell of interest in retconning Sulu as gay after George Takei came out kind of died down…
I was just coming in to mention that one. There are a number of gay and/or bi characters in Lackey’s Valdemar books. (Definitely worth a read!)
Lauren Lewis in Lost Girl
The protagonist in Aristoi has a male lover and was going to have a child with him until he was killed (their bio-technology is good enough to ignore little things like them being the same gender) .
Charles Stross frequently features gay characters: viewpoint characters in Halting State and Rule 34 for example.
Like, there’s any need to retcon?
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Sorry he didn’t fit whatever stereotype you have for gay men.
Did he? He mentioned that they had sex, but I don’t remember us actually seeing them kiss.
I think it’s clear what was meant by this was that he doesn’t do or say anything at all that speaks to him having romantic inclinations towards anyone.