[Used Can]

Hmm... well, one can say that, if Athena doesn't remember him, he cannot apologise. Well, he can, but doing so would involve making her remembering a painful memory, and that isn't something Hayate would like to do.

So, the fact he became sad because she didn't remember him doesn't necessarily mean he loves her, but that he realised he wouldn't be able to attain forgiveness. Unless he states it, or shows it otherwise, his exact feelings toward Athena remain unconfirmed.