My character is always bi and I've never seen this. Even when I have a Female BF it's always been a girl showing us her hoohas.
Edit: I just reread your comment. And you said if you're a girl or gay guy. I misread what you said. My bad.
With that context in mind I kinda wish it was more 50/50 like. If you're character is bi and you have a Female bestie. Then you'd have a 50/50 chance of spawning the Guy. Just like if your a bi Female with a male bestie you should have a 50/50 of spawning the Girl.
But either way that's pretty dope, and I didn't know about it because I'm always playing a bi guy character.