Setsuna doesn't tell Michiru how it had ended in that other life-time. They were all different people then, with different motives and different reasons for the things they did. After all, as a spectator for most of her existence, Setsuna willingly admit that she hadn't the first clue to why people did what they did. She could predict their actions, but motives were always a tricky subject matter for her.
History repeated itself, but never the same way twice. The reasons it did so were always different, even if the end-results may not have really changed. "You don't think it'll work, do you?" Michiru asked her friend, surprising the older woman.
"What won't work?" Setsuna asked, calm but weary.
"Haruka and I," Michiru supplied nonchalantly, as if they were discussing the weather or what to prepare for dinner that evening.
"I don't believe I know anyone capable of escaping a set type of destiny." Setsuna answered vaguely.
Michiru smiled a little. "Perhaps that is not the problem we are discussing at hand," the aqua-haired woman speculated with equal vagueness. In the silence, each sat and pondered on the life they were unfolding, piece-by-piece. Setsuna did not ask Michiru which part of her loved Haruka. Michiru didn't ask Setsuna to turn back time for her so that things could be different.
"Perhaps not," Setsuna agreed in the long silence after.
Michiru only hummed a little tune and turned to watch the birds flutter from the roof.