And sometimes the two people who are in love are so incompatible they are better off being separate because otherwise they will cause each other's ruin.
Although Pope Benedict XVI said any reunion must be without morphing or absorbing, the truth is that the Orthodox see the reunion possible when the Catholics become Orthodox again, and the Catholics imagine the Orthodox becoming like the uniate Eastern Catholics. Fat chance.
Just as the Orthodox Church is defined by the first millennium, the Catholic Church is defined by the second millennium, which are night and day.
Theologically, any reunion at this point would require one side giving up part of its belief and that is just not very likely, just as the Council of Florence discovered.
I think, the Orthodox Church is primarily defined by the Muslim and Communist oppression, but a time will come when she heals.