For the majority of people, what they love exists only in the imagination. The object of their love is not the man or woman of reality, but what he or she is like in their imagination. The person in reality is just a template used for the creation of this dream lover. Eventually, they find out the differences between their dream lover and the template. If they can get used to those differences, then they can be together. If not, they split up. It's as simple as that.
— The Dark Forest
by Cixin Liu