Torrie
astray ay-ay-ay
That's what I thought, too. Besides, my take on that is that Aerith lives with the knowledge that she is the last Cetra. The last half-Cetra, to be precise, because the last pure-blooded one died before her own eyes.When I read this I thought she was astonished with the idea of having kids because of her knowledge of her dead. We already know she has knowledge of future events, and her resolution screams "I'm gonna push forward, even if it cost my life, for the sake of the planet".There might come a day where she would no longer be ‘the final descendant of the Cetra’. She imagined that scenario in astonishment and fixed her eyes on Tifa. She then flustered ―
She might have never thought that there might be other Cetras in the world, which means there's still a possibility for her to meet someone from her race and start a family. In this scenario, she would be saved by the bell because Zack is long gone, and if she'd had kids with him, I'm sure she thought they would have been normal human beings without unique Cetra abilities, and she would have had to choose between having a good time with someone she loves or preserving her race with someone she doesn't have any emotional attachment to.
Or what if she realises that she still might fall in love again and even have kids and live a happy life while we assume she hasn't quite moved on and keeps missing Zack every single day, and that emotionally constipated blondie doesn't quite fit her already experienced relationship model (and is attracted to another girl anyway).
Or indeed she knows she's going to die, but it's not quite certain if the white materia is to be passed on from Cetra to Cetra before the owner's death and she definitely doesn't have the time, but maybe she thinks hey, hold on, maybe I won't die this time around?