Hyperion by Dan Simmons (the whole cantos, all books).
The finale in the last book really touched my heart and let me think about love and how much to value the time you have with each other.
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I never thought to find this in a science fiction space opera - I was shocked.
The idea in the book I am talking about is crazy and I cannot fathom how one would feel if something like this really happened. It is wonderful and sad at the same time.
That said and totally apart from it, the whole thing is a masterpiece. You have to read all books of the canon, even if the first book with the unique stories seems strange - I could not put it down though. Apart from that it also has great storytelling, wonderful language, crazy ideas (a house with rooms on different... no spoiler :) and more.