In 1450 the Eccumenical Patriarch and the Metropolitan of Kiev were puppets of a puppet-emperor. When the Eastern representatives at the council insisted that they must ratify any statement in Synod form in Greece, the Latins ignored it, publshed the statement anyway and sent them packing. (Even NewAdvent catholic encyclopedia admits this much).
It would be interesting to see what would have happened if they had been allowed to convene in Synodal form, but seeing as the Latins pre-empted this in an attempt to unilaterally decree a decision, it is on the Latins for destroying any chance at union.
About a century latter Rome again tried this, but dispensed with any pretense of there being a mutual union. After the Union of Brest any Orthodox were arrested or killed, many tortured.
Myself, I have no dog in this fight. I am not a Christian. I guess that the Latins thought that whey were in a better position to bargain than the Orthodox. I sure agree, it is bad manners, at least, to demand rudely what you could get by willing cooperation.
I also don't care for the very foundation of the Post Constantine empire: One G-d, One Empire, one Emperor. The Coptics were so oppressed by the Romanai that they welcomed the Muslims. Alas, the Muslim tolerance did not last.
The Crusades did not workout either, though Richard I of England carried the cresent and star (symbol of Diana, a patron of the ancient city of Byzos, and the star of the Virgin Mary added after Constantine) his support for Constantinopolos) on his crest while on Crusade.