It may not have been handled well or built up well as a twist, but Luke and Leia’s relationship works better as a fraternal one than a romantic one.
Which reminds me.
The decision to all but gut the Luke-Leia-Han love triangle from TESB was a mistake. It’s made it easier for Lucas to shoehorn that terrible sister retcon in when he made ROTJ.
Yeah, I think he just couldn’t come up with a way to resolve that triangle neatly. He wanted Han to win, but at the same time, he didn’t want Luke to “lose”, if that makes sense.