I understand that this is the LTD thread, but I also think we need to put this into perspective - I don't think we're really supposed to be arguing whether the love triangle exists at all because that's a false premise. What we are arguing is the actual nature of this triangle and I think we sometimes fall into the trap of containing this in a binary of platonic/romantic, and people are just not that simple, and if they ever were, then we wouldn't be discussing this at all. I've definitely joked about the war being over, though, since I think we've always had the definitive answer to "Who does Cloud Love?" and that's always been Tifa (to be clear, mutual romantic feelings, and not feelings of mutual best buddy-hood).
Given that the premise is about who Cloud reciprocates his feelings with with, I don't think that anyone should be working so hard to deny that Aerith does have feelings for Cloud because we really should assume that she does. Regardless of whether or not this is based on her residual feelings for Zack, they do exist and she feels them fully and they are directed to one person who we know for sure is alive. You can, indeed, catch feelings for someone in weeks worth of time with the right factors, and you can fall in love without knowing who someone really is - people do that all the time and for all the wrong reasons, but they do, and its unfair to suggest that the love they're genuinely trying to give is somehow indicative of an attempt to emotionally defraud.
@Hix puts it well here, I think, especially the fact that Aerith isn't doing any of this to harm anyone, but that this is all because she was harmed herself. Losing Zack was a formative moment in her life - losing someone so dear
despite their promises changes her perspective, and it must feel cruel to watch two others, so much like she had been with Zack, somehow find their way to each other in a way that she and Zack were not to be.
She seems at least somewhat cognizant of her own attempts to recreate the magic of falling in love with Zack and seems to understand that it isn't fair to Cloud, and her date feels like a true attempt to declare that she has decided to take her first steps away from her previous behaviour of unknowingly encouraging his SOLDIER persona and towards a more honest understanding of who he really is - a boy she knows she doesn't know the same way that Tifa does, a sore spot she has made clear she is jealous about (but for the sake of argument, if she is serious about winning his affections, then yes, rightly so; this is an uphill battle for anyone else and they should know that).
@insanehobbit hits the nail on the head here, I think: she wants to be fulfilled in knowing she can feel this again, whether or not it can be returned, but often times, it doesn't need to be - love is for giving, not taking, and she wants to be able to do so. It's really sweet and really sad, and I think part of this is the failure of seeing everything through Cloud's eyes.