The knighthood thing is mutable. It needn't be knighthood, in the Northern European sense, but, the idea of binding Diana's friends together, in service to her cause, ..as their royal princess and commander in battle. In this service, would Steve Trevor be one of four or five of Diana's chosen companions, each with special skills, useful in WW stories - fighting, weapons, knowledge of magic, tech skills, Amazon training, etcetera.
Among Trevor's select skills would be ..the obvious. Woo'woo!
Superman and Lois, while enamored of each other, aren't equal partners on the battlefield, where Lois is clearly outclassed. Why should Diana and Steve be partners, just because she is a woman? He's nowhere near operating on her level, and what they do to each other in the bedroom has nothing to do with that.
Anyway...Steve working for or under Diana, anyone?
What if Steve, while wanting to completely give-in, was the one resisting loving submission to Diana, instead of the other way around?