Towards the end of the game, for example, Polka picks her fortune even though the fortune teller says it's going to be bad luck, because she doesn't believe that anything is set in stone. And even in this cyclic world that repeats over and over, it isn't.
If you notice when Polka is falling in the introduction scene of the game, she says (paraphrase), "I wonder if I blew him a kiss, would it reach him? ... I guess not." At the *end* of the game, though, when she's falling, instead of saying "I guess not" she says "I hope so." It's a minor difference, but it shows that things aren't exactly the same in every cycle, that the characters still have control over their own thoughts, words, and actions.
This is also made evident when she asks Frederic if he knows what she's thinking. He says of course, since it's his dream, and tells her what's on her mind. Later though, he finds out that he was wrong, and Polka tells him that she was thinking of leaving Tenuto. I believe that Frederic guessed wrong because he stated what she had been thinking in the *previous cycle,* which was different than what she was thinking in this cycle.
Also, if anyone notices, after she says "I guess not" in the first scene, it looks like something shiny/sparkly is coming out of her. To me, this represented that her astra was dimming. Whereas in the ending, when she said "I hope so," her hope kept her astra burning bright. I think this possibly matched with Allegretto's actions this time around. Her mother saying that she had finally met someone who matched her astra, even though she had already met Allegretto in previous iterations shows that everything was perfect enough, bright enough, hopeful enough, loving enough, or whatever the condition(s) may be for Frederic to have the strength to finally embrace death.
Unfortunately, we don't really get any insight into Allegretto and the others' lives in previous go arounds, but my guess is that it's the same situation as with Polka, that subtle things (and maybe some not so subtle things?) in their lives could have varied in different cycles. Even though it was Frederic's dream, these characters were still very real, and in charge of their own destinies.
I also think that the dream was more than a dream -- that the world with Forte, Baroque, etc. turned into Frederic's Heaven at the end. Even though he embraced death, he and the other characters didn't disappear because he was now in Heaven (or Nirvana or whatever you want to call it). And this was important that he embraced this world/the flowers/Polka as Heaven's Mirrors rather than Death Lights, because this allowed the world to keep existing as his Nirvana rather than disappearing.
Anyway, that's just my opinion, but I probably read too much into everything. I hope I at least made sense
