I'd love to know how crazy the Luke/Leia, Han/Leia, Luke/Han shipping got.

Also, in case you were wondering, Leia being 'the other' Yoda was talking about was more or less forced on George Lucas by the divorce from Marcia Lucas. She had cheated on him with a guy installing the skylight at the ranch and the fallout was very messy (pretty much everyone in the industry cut ties with her because Lucas was such an awkward but lovable guy who was totally devastated by it) and the divorce ended up costing Lucas, especially since he got custody of their daughter. Because of this plans for the sequels had to be cancelled and 6 had to be the finale, so while Vader was always planned to die, Palpatine was supposed to live and take Vader's place as the main antagonist and Luke's sister was a girl named Neleth (or something like that) who was also in hiding. Because of this the 'other' mentioned in ESB had to be either an existing character or else make RotJ really freaking long to have Neleth in there but not get much development.

It couldn't be Han because of how skeptical he was of the Force, it couldn't be the droids, it couldn't be Chewbacca because people might see it as too ridiculous, it couldn't be Lando because a lot of people weren't eager to forgive him for betraying Han (at the time) and it couldn't be a minor character like Wedge, so Leia was the best of a bunch of bad options. It was either that or leave 'the other' hanging and never address it.

Yeah, their daughter was adopted and custody battles are always messy, and I assume that was a big part of it.