Why did they break up??? Estefania and Amadeu

In the book, she said he only wanted to go to Brazil for himself, that it had nothing to do with her. That it would have been a trip to the inner depths of his soul. She says something similar in the movie too.

Yes, she said that she didn't want to go to Brazil. She felt like going so far away wasn't in her life's plan. Since they already made it and got out of their country dictatorship she was already ok but he was not. He wanted to go further. He said he would spend his life writing books - in the beginning we learn by his sister that before studying medicine his truly wish was to be a philosopher and a writer - and also said they would go to "a world where only you and I exist" and "invent a language that only you and I understand". This was the moment she started crying and realizing that they were not meant to be together. He was idealizing his dream, not their dream. Remind that their passion resulted of that stressful, exciting and danger life they were having in the Resistance. As you said, they just started their relationship so that was the moment where they were knowing themselves and each other passions, dreams and thoughts. So she said he was asking for "more than I can ever give you" which means that she could give him her love but she could never give him her own life. Well, at least this is my interpretation.

I understand some confusion tho. I can agree that the scene was not very well explored cinematographically. They could dramatize a bit more. For a break-up scene in a key moment the segment is too summarized.

But, well, basically they had different dreams and views about life, philosophically speaking. He was a meditator, a metaphysical and a poetic man and she was a practical, reasonable and a pragmatic woman.

Very good point.
And it was certainly not explained in the film although, as you say, the thirty seconds conversation was supposed to make it all plausible..

SPOILER: The break-up did seem abrupt and somewhat contrived, almost as if someone (a producer?) feared the movie going longer. On another level, though, Amadeu was a man of ideas and internalized passions who looked beneath the surface of things, thus his power as a poet; Estefania was a pragmatist who memorized facts extraordinarily well without ever really thinking about them beyond their usefulness, thus her part in the revolution without the expected rhetoric.

There was a parallel between the two couples: Estefania amd Raimond were both professors, whereas Mariana and Amadeu, though both professionals, were governed by emotions. The two worlds are not necessarily exclusive, as Raimond seems to learn in the end as he apparently does not board the train back to Bern and instead responds to Marian's request for him to stay with her. It is almost as if he instinctively has explored the other couple's failure as a last-second wake-up call for his own fulfillment in a relationship.

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