Like peanut butter and chocolate, that is to say the combination that springs to mind after you realize you can't get your first combination and actually you might prefer. In the context of the DCU, both the man in the street and fellow superheroes think they're hooking up. Lois was once briefly jealous and probably because Clark was naively dumb enough to tell his wife about how they kissed once, how Diana created a statue that envisioned them together and how she put the moves on him once when they were trapped for a thousand years in a really bad story, er, I mean Valhalla. But beyond that, every time any creator gets an opportunity to tell an out-of-continuity story, he (and it's usually a "he") hooks them up. Kingdom Come, where the epilogue has her pregnant. Distant Fires has humanity destroyed and Superman and Wonder Woman having a son who winds up being the last survivor of earth who is sent by a power ring rocket to another world to start the Superman cycle again. In Red Son, she loves and supports the fascist Superman, only wind up crippled as a result (but that red & black outfit is nice). In Act of God all those with powers lose theirs and after falling into despair and losing Lois, Superman winds up with Wonder Woman and once again give birth to a near god. In Secret Society of Super-Heroes she loves him but never tells him and in Whom The Gods Destroy, Lois is Wonder Woman, so problem solved!
Out of all of these, I thought Red Son came closest to what it probably should be like. Given Diana's worship of Greek gods, what is Superman but Apollo on earth? If the legends are true, he's technically descendant of the Kryptonian god, Rao, who took a human bride to star the "El" family. I don't think she'd every really romantically love him because he was too much like what she worshipped. Similarly, all Superman wants to be is human, so the last thing he wants is a divine, royal girlfriend. The farmboy in him would ironically always look up to her.
And since everything is better with pictures: