JLU was made by a Batman fanboy who thinks every woman wants Batman. WW's character was destroyed because she was made as a girl who doesn't know what she wants and she allways tryied to get under Batmans skin. The relation was force in few comics and those were bad writted. It din't go anywhere.
You just rpooved you only watched JL cartoon without reading any comics. ''Wonder Woman and Batman always had sexual tension between them'' ? Wonder Woman's character was badly modified and destroyed by bruce Timm who believe that every woman want's Batman when that is not true.
What I am saying is that despite how he was raised, over time Clark Kent could loss himself too Superman if there isn't someone to remind him of his humanity. Plus we don't know how long Superman will live for, because in some comics he seems to age like a normal human while in others he is immortal or at least ages slower.
And I am not saying Wonder Woman could not be an equal too a male counterpart, its just anyone would be shadowed by Superman. After all he is DC's most iconic character and I just think Wonder Woman should never be expected too stand aside for anyone.