Cora deserves an Asari love interest, c'mon.

As melbella said, bad writing is the answer. Most of the MEA character have the same desease as DA2 characters (at least for me) too space to a single argument of conversation that make the character one note and monodimensional.
And I'd go with obsession over bisexuality. I can't see it possible for her living with the Asari and not have a single experience with one if she had any kind of interest in women. Is neither conform to the ME lore (where sexuality is not a problem) nor to the Asari, who are probably naturally more inclined to be lesbian than bisexual.

Yes, just came across that today.  Not sure if I never noticed or simply didn't trigger the dialogue.  It's also been a long time since my last time playing.  Still, nothing she said indicated that gender was the issue.  She seemed to imply that even when the did engage in fraternization, it was usually just a one-time thing.  That could also be a reason not to engage.  I don't think we can really draw any full conclusions about whether or not Cora would engage sexually with an asari, even if not with a human female.

You'd think that BioWare would have thought a character like Cora would have been ripe with potential in having a character explore her sexual identity that would not only be unique for a romantic character, but would also be uniquely relevant to the Mass Effect universe in general. A human female soldier who gets to train under the guidance of an all-female race and through their guidance (and other encounters) Female characters in Mass Effect Andromeda who you can romance don't really have anything to say about why they're attracted to women. Suvi has a moment where she says any relationship with Scott wasn't going to work, but that's about it. Vetra is just game. Peebee is just game. Cora could have been the unmistakable lesbian character who's sexuality is associated with this universe.

Maybe bisexual?  With asari, it's a tough call to make.

That would be a contradictory retcon since Cora specifically states she had to explain to an asari in the past that she isn't interested in women. 

Since she's straight I don't really believe so, but I won't deny the idea is hot as all f...