Pre-AC. They didn't need ghosts; their own memories haunted their lives.
She didn't have the heart to banish it from their lives.
Ghosts, Tifa thought, didn't even have to be dead. It just so happened that this one was.
(Sometimes she thought Cloud was even more of a ghost than the dead---he flitted in and out of their lives, there but not quite, and when she tried to make him stay, it felt like she was trying to grasp wisps of smoke between her fingers.)
Tifa was standing by the kitchen counter, pretending that she was drying the dishes. In reality, she was watching Cloud. Cloud, in turn, was staring at his drink. They didn't need ghosts; their own memories haunted their lives, and that was just the way things were. Tifa had pondered this and she had decided that she didn't quite mind. Aerith was fine company, after all. She just wished that Cloud would stop going around with that lost look in his eyes (which he probably thought he hid from her---he never meets her gaze anymore) and sit down and /talk/.
He stood up and left without looking at her. Tifa sighed, throwing the cloth she was holding into the sink.
Aerith's ghost was there, in the emptiness of the pub and the flowers Marlene threaded in her hair. She was in Denzel's shy smile and the cup of coffee Cloud had left untouched (it had gone cold by now, for sure) on top of the kitchen counter.
She was everywhere and she was always with them, but Cloud didn't see that. Tifa wondered what it was he was searching for.
Even more, she wondered why he still hasn't found it yet.