When I was younger watching ANH for the first time, I really believed that Luke and Leia were going to end up together at the end of the film. Then in the TESB Han suddenly became the third wheel and because Luke was out of the picture on the MF, Leia eventually succumbed to his advances. In the scene when Luke is calling out to Leia I took it that the reason she was able to hear him was because deep down it was Luke who she truly loved not Han. Then it was revealed that they were brother and sister, which changed everything.
That’s a pretty accurate description of reality before ROTJ. “Younger” had nothing to do with it.