Bruh! This is the #1 thing I hated about BvS. He was with her the whole movie, flirted with her, did research on her, discovered the old photo of her from the past, And asked her to join the fight. Then they put in the stupid line.
That was a great opportunity for Batman to deliver a great line. Even if they couldn‘t think of something cool Batman would say; they could have just given us a great Guy Line. “Damn right she is”, “Yeah. She’s my muscle”, anything would have been better than “I thought she was with you”.
Another issue, it was clear from BvS and the “mouse scene” from Justice League that Snyder is inspired by the work of the great Dwayne McDuffie. But he failed miserably to deliver any type of interest between the two characters and instead always has Diana dwelling on losing Steve. If these directors don’t know how to execute something they shouldn’t even try it.