In retrospect, Batman looks like a dope saying "hurr durr I thought she was with you".
You're the one that's been following her around the entire movie there buddy. You even know what she looks like as Wonder Woman thanks to that picture you found surfing Lex Luthor's porn folder.
That actually is weird. Did he think the guy being assembled out of spare parts was "with" Superman too? Or that Diana was in cahoots with Clark even though she'd been around for decades (and off in other countries) prior to his arrival? Should have been a "trailer only" line like Luke's bit about the Force being strong in his family.