I would say the romance in Captain America was minimal compared to the first movie, with Haley Atwell's Peggy Carter, which I think effected how it was implemented (or lack there of) in future movies.At least Sharon Carter was a thing in the comics and also the romance in Captain America was honestly kind of minimal. Even compared to say the Iron Man or Thor movies. As yeah it was important but it wasn't as strong or as integral to the story as Diana and Steve Trevor was. Plus yeah while Batman and even Superman have had more of a trail of crushes, Wondy really hasn't. Thus why Steve Trevor constantly just gets rebooted in the comics to be around when Diana's around in the current time frame. And any other major pairings people know involving Diana are with relatively known characters like the afformented Bruce Wayne and Clark Kent. So I can see wanting him around. Again though I hope that since Jenkins was annoyed by Diana's depiction of not being over Steve Trevor in Wonder Woman there's a reason why he's brought up again like... nearly seventy years later for her.
Wonder Woman has had other love interests, albeit not in as significant a capacity as, say, Catwoman and Lois Lane are for Batman and Supreman. It's only really been recently that they've started to re-emphaize Steve as Diana's main love interest.