I often wonder if Steve’s game doesn’t get stepped up, because they’re afraid to explore Diana’s romantic and sexual side in a situation that’s not “perfect?” They definitely need to do it for the reasons you mention, but unfortunately nothing replaces the weight of having history and exploration during different eras, especially when it was off the table for decades.
Trevor Barnes are Rama are the two potential love interests, Post-Crisis, that I remember being explicitly set up as romantic foils for Diana during that time and before the DCnU.