You know, I never really thought of it that way, but Lucas sewing up the love triangle by making Leia “the other” in Return of the Jedi, and turning it into a big bloodline thing, it really kinda screws up the conversation in Empire Strikes Back.

Luke is hellbent on leaving because he saw a vision where Han and Leia die if he doesn’t intervene.
Ben says “you don’t know that to be true because even Yoda couldn’t see it.”
But Yoda basically says “Well, look, even if you DO go and save them, it’ll ruin everything. So you can’t go.”
So Luke leaves because he’s Luke and he can’t not. And Yoda says “there is another.”

But if Yoda knows the other is Leia, and Leia is the one that is going to die if Luke doesn’t get there to help her, why is he so nonchalant about her not being saved? At best, he’s saying “eh… she’ll figure it out. Probably. Maybe.” and at worst he’s saying “We don’t need our all-important backup plan if you just stay here and let her die.”