I think Rachel\Juliet's flashback in "The Incident" is the second most useless fb moment in the whole Lost storyline. Do you agree? I mean, they showed us that divorce-moment only to connect Juliet's strange sentimental behaviour to a deep cause? I'm still sure she changed her mind 108 times in-a-row only because I) she's dumb and II) she was in that period of the month.
By the way, first most useless fb moment is the Jack's "Stranger in a Strange Land" tattoo, of course!