Look dude, it's been 15 years... that's longer than Asuka had even been alive
prior to meeting Shinji in the first place. She had a bit of crush, sure, but then he refused to fight when she was trapped in an angel eva but broke the damn world
when it happened to Rei, so she has to be able to see the writing on that wall. It is wildly unreasonable to think she hasn't moved on a LONG time ago.
That said, there is precisely one person in Wille that shares her 'curse of eva' business (which has to make relationships a bit uncomfortable for most potential partners) and they happen to work together all the time, so if the two of them aren't completely straight it isn't unreasonable at all to think they might hook up eventually. Plus it's just cute.
Didn't Shinji refuse to fight Asuka in Eva-03 to protect her in the first place? He said something like "I want harm her even if I have to die" if I remember correctly.
Narratives don't work on the "what would make more sense" logic. If it was the case Misato would have detonated Shinji's head with no hesitation at the start of Q and then they'll have lived happily ever after. That's what any real people with her position would have done, but she didn't and it doesn't make any logical sense if you think that she had 14 years to take decisions much more difficult than that and she probably assigned very good men and women to suicidal missions (that's what happens in those kind of scenarios). She didn't because it makes sense for Shinji's character and his future path to redemption/salvation. Shinji is the plot, Shinji's what actually matters for the plot. I don't think that in NGE or Rebuilds there's a single character that has interpersonal relationships that could be defined as "normal".
Same story for Asuka: of course she lived before meeting Shinji and she also lived after Ha, but does it really matter for the plot? I don't think it really does. we don't have a single word or video frame about it except for a "I'm exactly as you remember me 14 years ago but conflicted about you" which was of course something Anno came up for Shinji. Even during Ha she changes because she meet Shinji.
In a story a character feels how the author choose it to feels, what happens before the story it's mostly useless unless it is shown somehow or referred to.
I'm not even bringing up the good amount of visual storytelling that it's in Q, the cuts to Asuka's amazed face to Eva-01 eye, the close up of the hand scene at the end, even the song about love that start with them in the desert.
On the "it's cute" I kinda agree tho, they have a character design that mix in a really good way.
Also would make sense for Asuka to have a story with Mari in the 14 years time skip in a real case scenario? I honestly don't know, we can presume she was at least straight, does she likes women too? It's safe to say no based on statistics. Can she turns gay because of lack of any other options? I really have no idea.
I think it's likely when Shinji does return Asuka's feelings for him will return somewhat but I don't think its unreasonable to assume that Mari/Asuka might have had a bit of a thing in that time.
I kinda ran with that theory in my fic, that over the course of the year Asuka/Mari had not a full relationship but were there for one another because, as NemZ points out, they both share the curse of Eva stuff and are the most likely of all people there to understand one another.
She's the one that probably understands Asuka the most and she's the one hinting at Asuka having romantic feelings for Shinji in Q.