So we're here talking about the brutality of the West toward that bastion of civilization in Eastern Rome, Constantinople. I asked if anyone actually knew the history of Constantinople and a few of you confirmed that you did. I'm curious if any of you recall the proceeding years leading up to the assault on Constantinople by the Venetians and Normans? Specifically, do you recall the imprisonment of 'every' single Venetian in the Empire but the Emperor Emmanuel... or the Massacre of the Latins in April 1182 AD under Andronikos I Komnenos? How about Emperor Isaac's deal with Saladin to hinder the Latins during the 3rd Crusade? I'm thinking of one Frederick of Germany being delayed by Isaac for the benefit of Saladin against the English and the French? What about the 4000 survivors sold into slavery but the Emperor to Muslim Turks?
The Massacre of the Latins occurred in Constantinople, the capital of the Byzantine Empire, in 1182. It was a large-scale massacre of the "Latin" (Roman Catholic) merchants and their families, who at that time dominated the city's maritime trade and financial sector. Although precise numbers are unavailable, the bulk of the Latin community, estimated at over 60,000 at the time,[1] was wiped out or forced to flee. The Genoese and Pisan communities especially were decimated, and some 4,000 survivors were sold as slaves to the Turks.[2]
Following the death of Manuel I in 1180, his widow, the Latin princess Maria of Antioch, acted as regent to her infant son Alexios II Komnenos. Her regency was notorious for the favoritism shown to Latin merchants and the big aristocratic land-owners, and was overthrown in April 1182 by Andronikos I Komnenos, who entered the city in a wave of popular support.[1][10] Almost immediately, the celebrations spilled over into violence towards the hated Latins. Although Andronikos himself had no particular anti-Latin attitude, he allowed the massacre to proceed unchecked.[11] Many had anticipated the events and escaped by sea.[2] The ensuing massacre was indiscriminate: neither women nor children were spared, and the Latin priests and monks received special attention. Cardinal John, the Pope's representative, was beheaded and his head was dragged through the streets at the tail of a dog.[2][12] Ironically, a few years later, Andronikos I himself was deposed and handed over to the mob of Constantinople citizenry, and was tortured and summarily executed in the Hippodrome by Latin soldiers.
http://en.wikipedia.org/wiki/Massacre_of_the_Latins
My guess is you don't spend much time reflecting on such details because it isn't convenient for you to do so. As I've said evils have been done by East and the West but it doesn't seem like the East remember their own misdeeds because they are too eager keeping track of the misdeed done to themselves but history is a two edged sword people.
Then why do you continue to cut yourself on it?
We don't "spend much time reflecting on such detais" here because they have nothing to do with the OP, except further justify dwelling on 1204. As you point out, the Roman Emperors called the West as allies and intermarried with them as "allies." Said "allies" proceeded to further undermine the empire on the frontier with Islam, setting up its own rival Patriarchate in Antioch and Latin state in 1098, and massacring the Muslims with the capture of 1099: the Orthodox having been expelled as the Crusaders approarched, a harbinger of the new relations between the Orthodox and the Muslims, the latter permanently now seeing the former as an innate fifth column. Said "allies," as you point out, proceeded to turn over economic control etc. to the West, a fact even the great unwashed in Constantinople picked up on. But the emperors continued to foolish take enemies as friencs, and the populace continued to rip the fleece off the wolves, which forced them out into the open in 1204. And again, that, not 1453, was the turning point of the Empire.
The Eastern Emperors asked for aid from Western Christendom
A stupid move on the part of the emperor, for which neither he nor the empire received anything.
and the West gave them her sons but when those sons needed the Eastern Emperor to have their back at the Siege of Antioch, he left them to die without water or aid during a counter-siege by the Turks.
Many Orthodox, notably Patriarch Simeon of Jerusalem (in exile on Cyprus) and the local Greek and Armenians (who had been expelled from the city), sent aid. Aid came from Constantinople even after the Roman Tacitus left.
But they didn't die and they managed to win against the Turks by leaving the protective walls of the city and meeting them in open combat.
They spent their time jockeying for position and who was first, too busy to listen to or take cognisance of the Roman general and legate Tactitus, and then Bohemund, scheming to take Antioch for himself, told Tacitus that the other Crusaders were plotting to kill him. So Tacitus left.
They won
Because Bohemund bribed a Armenian guard in the city to open the gate. Bohemund then told the other Crusaders that he would get the gates open, but would do so only if they recognized him as lord of the city. Raymond of Toulousse insited that the city belonged to Emperor Alexis, and others scoffed at Bohemund demand but facing approaching reinforcements, theymostly caved into the demand.
and they felt no loyalty to the Emperor that left them for dead at the hands of the Turks.
So Bohemund claimed, to cover up his treachery and scheming. Raymond and Godfrey of Bouillon didn't buy it, and Stephen of Blois refused to advance Bohemund's agenda and left.
So they didn't turn Antioch over to Eastern hands and kept it to rule over it for themselves. You may look at it any way you wish but in those days loyalty between brothers meant something until you failed to live up to your bond.
Is Bohemund's lying constitute "failure to live up to your bond," bearing false witness that his fellow Crusaders Raymond, Godfrey, Stephen etc. were going to kill Tacitus, and slander that Tacitus' departure was treachery/cowardice?
From the eyes of those Western Christians who bled to retake Antioch the Emperor sold them out.
Their eyes were evidently blinded by Bohemund. Btw, the Turkish commander of Antioch was catpured and executed by the Syrian Orthodox.
The turning point of the Empire was the end of the Macedonian Dynasty... 1130 AD
? The Macedonian Dynasty ended in 1057, its territory was this:

It was succeeded by the Komnena, whose terriotry was this:

Doesn't look terribly enemic to me.
as there was a revolt just about every single year during the 12 Century.
The Empire looked like this in 1180:

It looked like this after the Crusaders had their way with her:

If the Emperor didn't want Westerners within his walls he should have built his own fleet instead hiring Venetians for ships and trading rights. If he didn't want to have revolts and unrest within his kingdom, he shouldn't have hired so many mercenaries to fight for him and fought his own battles as his more noble forefather led in the field of battle before him. No, Friend, the Empire didn't 'turn' on 1204 AD. It was already decadent before then.
Emperor Alexis recovered his sanity and kicked Bohemand's Norman a** and forced him to sign the Treaty of Devol, in which Bohemund swore to submit to the Emperor, swearing
"I swear to thee, our most powerful and holy Emperor, the Lord Alexios Komnenos, and to thy fellow-Emperor, the much-desired Lord John Porphyrogenitos that I will observe all the conditions to which I have agreed and spoken by my mouth and will keep them inviolate for all time and the things that are for the good of your Empire I care for now and will for ever care for and I will never harbor even the slightest thought of hatred or treachery towards you [...] and everything that is for the benefit and honor of the Roman rule that I will both think of and execute. Thus may I enjoy the help of God, and of the Cross and of the holy Gospels."
http://en.wikipedia.org/wiki/Treaty_of_DevolHe also has to give up the Latin usurper he put on the cathedra of Antioch and accept the Orthodox one, in addition to giving back to the Empire the land he stole. Bohemund never returned to the East, evidently learning his lesson.
In 1177 Manual recovered from the defeat of Myriakephalon, defeating a force of picked Turks at Hyelion and Leimocheir, and following up with raiding on Seljuq territory, having been able to gather armies to join that sent from the capital. The Romans still had the stuff.