LOL I think Subaru said that in order to look like a different person...of course Akai wouldn't say that kind of things,but if he's in deguise,he has to act differently,or else the BO would find him(and kill Akai and Rena)
Moreover even Ai didn't react at that comment,because she was sure he's Akai.
Chekhov explains the Akai=Okiya theory better than me,so you should read her posts.
If you have any doubt at least you can trust Ai's flashback about Akai,Ai has a good memory^^
So yeah,Ai will be heartbroken concerning Akai and his link with Akemi's death,which will really interesting IMO.