I didn't like how they handled Ander's bisexuality either,and I definitely see no reason why he wouldn't mention Karl to a femHawke.
Yeah, that's one of my biggest peeves of that romance. Karl was used as a way to open up the path to finding out he likes men, so a male Hawke can pursue him. But I thought it added more depth and sadness to the outcome of Karl's chantry tranquil stuffs so I wish they would of kept it in no matter the gender.
One thing I did like about Zevran's bisexuality. He brings it up to womenfolk, and basically wants to know if knowing that about him is a dealbreaker, and if so best to find that out now. I liked that you could tell him you're not bothered by it at least. Better than the lack of gentle let down when Anders flirts with male Hawke.
Hopefully it'll be dealt with better in DA:I if the same gender hits on us again and we're not interested. Only having a mean way to handle it did not jive well with me at all.
And one would hope it'll go in reverse if they bring back straight/bi/gay romances. Couldn't even so much as flirt once to test the waters with Alistair or Morrigan. Better to tell me they ain't interested than to not have the option at all.
And to bring this back on topic.. Still hoping Cullen is available to all.