THE EASTERN CHURCH HAD BEEN FIGHTING THE ARIAN HERESY & islam FOR CENTURIES. The papal european hordes had already sacked and destroyed Constantinople during the Crusades, Remember?
At one point more eastern Christians belonged to Arian churches than the EOC.
Imagine if I was to tell you that the fish hat "dagon" wearing Pope was the leader of the ancient mystery religion Babylon, he's satan's man on earth; or something that egregious? Then I sent an army to sack and destroy Rome. That's how the EOC fells about Rome; you poured gasoline on top of St. Sophia's in a sincere effort to destroy our church.
When this issue of "The Great Schism" comes up at interfaith dialogues, it's always explained as simple playful political tit for tat by RCC apologists. Trust me it was a poisoned and fatal dart aimed right at the heart of the Eastern church intended to destroy it. Rome eventually got her wish when islam completely destroyed the city of Constantinople in the 1500's. With a small amount of Christian charity and military assistance it could have been easily saved. The papacy could have directed the forces of several european nations to come to her aid, but alas it was all about the primacy of Rome, so millions of Christians died. It's no different today.