Crazy thought but I think that long term:
-Steve and Diana breaks up at some point. Your first love is not always your forever love. Most of the time it feels like the relationship runs it's course after their first meeting and adventure. Maybe Steve hooks up with Etta while Diana goes on to date other people (maybe a woman).
-Steve and Diana gets into polyamorous relationship with Etta Candy (or perhaps others). It makes sense for Themyscirans to have more than one partner and I think Steve and Etta with their current characterizations would be open to it. Given who created WW, the polyamory thing is way too encoded in Diana's character for writers to enforce monogamy into it, imo.