I'm almost positive it's number as she says during the trailer "not even memories are safe from the darkness". Which makes me wonder if we just got the explanation as to why Aqua didn't stay with Mickey. They probably met up but Aqua was deluded by her own memories for so long that she thought Mickey was another hallucination and ran away or something, and thus why Mickey talks as if something sad separated him and Aqua.
I'd go as far as to say that Aqua was there so long by the time Mickey found her that she possibly attacked him thinking that he was an illusion. So he couldn't have brought her back even if he tried, at least not in that state.