I agree with you about Lois, and I’m glad they explored Superman/Wonder Woman, but I really felt that something was missing from each character in the relationship. I felt less connected. The relationship dynamic felt off to me. The experience really made me appreciate their strong friendship.
As far as romantic couples, I prefer both with other people (namely Lois and Steve, respectively, although Bruce/Diana is interesting) . While I’m often not a fan of Lois, I think her character fits better with Clark. When I like her, I think they both challenge and support each other in interesting ways. It’s weird for me to see him with anyone else, and there’s a sense that it won’t last.
Edit: As for Diana and Steve, I think he helps connect Diana to the human world and see that ‘normal’ men (although Steve is above average!) can be good and honorable and have similar ideals to the Amazons. Diana/Clark doesn’t really help either character stay connected to the people of earth/‘man’s world.’