Superman's a pretty decent guy and after he falls for Lois Lane, he immediately tries to be completely honest with her. The only trouble is that Lois is a bit confused as to what Superman's coming out about.
Or maybe Lois is way smarter than all of us and has figured out Superman's real secret. Who knows. I think I'll just enjoy the Batman cameo at the end of the clip and not question this too much. [Thanks, Erik!]