Ai-chan lives in that apartment building IIRC, several people elsewhere theorized that she was heading to the 1/25 concert.
@BigDnm: The pictures are from a stalker who posted them on 2ch, not from a tabloid. In fact no print tabloids have bothered to mention this (Tantei File posted about this but they are really unreliable, not at all like Friday for instance).
Really, like reyfer said, there's nothing in those pictures that suggests that Ai and Shun are a couple, they just don't seem to be paying any attention to each other at all, they're not even getting in the taxi together or holding hands or anything. They just have hats that look the same

I bet UFA and whoever Shun's agency is will let this pass.