I first started reading Wonder Woman in the 70's, so my opinion is she can ONLY sleep with him. In my (nieve) mind, HE is the only reason why she left Paradise Island, and her one and only 'true love'. They were made for each other (literally), and meant to be together.
Otherwise, to me, her sleeping around would conflict with the (tradtional, by our standards) Amazon rule of being 'man hating'.
I see it as, the Amazons did their wars in Ancient Greece, and learned to hate men... and harbored a grudge for thousands of years. Diana was born on Paradise Island, and while brought up to distrust men, the only ones she'd seen were statues of gods, and paintings. Having never seen one, she would obviously be curious about them, despite what her upbringing was... and irony or fate would have her fall in love with the first one she saw... Steve Trevor.
There are lots of fictional couples who just wouldn't make it if you broke them up:
(a few)
Superman and Lois Lane
Jeannie and Tony Nelson
Samantha and Darrin Stevens
Beauty and the Beast
Wonder Woman and Steve Trevor
One of my favorite old issues was #300, with Wonder Woman married to Steve on Earth-2, and their daughter Lyta Trevor, and the rest of the Justice Society married to their sig. others... it was nice to see a different spin on how Earth-1 could have been in an idealistic, down home way.
I wouldnt want them to become an old married couple either, like Lois and Clark... I like the chase.
Straight men have fragile ego's... how do you keep Steve from being intimidated by a woman who can clearly open her own pickle jars? (Althought the DVD Cartoon did VERY well).