Originally Posted by
Robanker
Absolutely. There's no way this version of Barbara Minerva was one hundred percent heterosexual, though I'm not sure she's aware of it.
With respect to Di, considering how she was still so single-mindedly focused on Steve, I can see her displeasure at seeing Barbara with Max is her general distrust of the latter as opposed to jealousy. She came across (at least to me) as the older sister to Barbara, but again it's primarily because the movie seemed so focused on reminding you "SHE AIN'T OVER STEVE, BRUH."
Had she been over him, I'd probably have read it otherwise, but that's not the Diana we were dealing with some six decades later.