This is my personal opinion of why Aerith was so drawn to Cloud.
Disclaimer: SquareEnix owns the recognisable bits.
Aerith.
Waiting: To remain or be in readiness.
I thought I'd moved on. I actually thought I was doing really well.
I mean, I hardly ever thought about you. I managed to embrace each new day and be happy.
I stopped always looking over my shoulder.
Then I met Cloud.
It was so strange.
Everything he did, everything he said, even just the way he stood, reminded me of you.
It was like… everything I'd pushed away…
Everything I'd tried to forget…
… stood right in front of me.
Do you know what really matters though?
I would get annoyed if Cloud did something different to the way you did it.
I'd get angry at him for being himself.
I knew then.
I hadn't moved on. I still loved you. I still waited for you to come back. That's why I always stayed here. So you would know where to find me, when you came back.
I hadn't realised that I was waiting.
I'm still waiting.