It's been said enough times before. An engaging gay character would and actually does keep his sexuality on the down-low. Cortez from Mass Effect 3 mentions his husband because he's in the process of mourning him - that just happens to be a good, believable and natural way to show his sexual orientation without having him re-enact scenes from "To Wong Foo, Thanks for Everything, Julie Newmar".
This just proves that a lot of studios start with an idea, a game design concept, a few meagre character concepts, and then wing it. Oftentimes, you'll see characters that are so much FLAMING in their nature that you lose all empathy for them or ability to sympathize with them. The same can be said of Don Juan types, too.
I mean, shit. I hated Zevran's ass from Dragon Age 2, and Isabella's role seemed to be limited to "I have boobs, I'm sexy, won't you please try and fuck me?"
I figure we'll see realistic gays on the day the industry will stop thinking every male protagonist needs to be this barrel-chested douchecanoe who only expresses himself in grunts and Army slang - or when female protagonists will honestly be seen as a means to show off a decent personality, rather than BOOBIES, OMG. GUNBOOBIES. SO HAWT.
Most male gamers are getting into their thirties. I can only hope that as we keep maturing, we'll get out of this ridiculous need to have our hormones be pandered to. In a sense, we're getting there. Nathan Drake isn't some grossly caricatural Alpha Male, we've had Ethan Mars as a conflicted and very vulnerable protagonist, etc.
So things are changing, and I think they're changing for the better. Still, there's always going to be a niche for the ridiculously endowed Femme Fatale with guns, the Neanderthal with a chaingun, or the sassy chronic fence-jumper. I can only hope they'll eventually become a very small part of AAA game development standards.