Bolivar's campaign for independence was not a failure in the sense that he did manage to end Spanish control over South America and create several independent Republics. Rather, his failure was a political one, for he didn't create Gran Colombia as a lasting, powerful entity and failed in his cherished effort to create a great Andean Confederation.

Let's start with Gran Colombia. After a series of failures that led to the fall of the First and Second Venezuelan Republics, Bolivar decided that the only way to achieve independence was for the Spanish colonies to cooperate and present a united front against the Spanish. He started to envision a great republic that united all the territory of the Viceroyalty of New Granada - that is, modern day Ecuador, Colombia, Venezuela and Panama, plus some territories that would later be lost or ceded to other nations. The idea of Spanish American unity was not a new one, nor was it entirely Bolivar's. Its greatest exponent was Francisco de Miranda, who dreamed of a great republic from Mexico to Argentina, with a capital in Panama. He would call it Colombia, in honor of Cristobal Colon (also known as Christopher Columbus to anglo friends). Miranda was the first leader of the Venezuelan patriots, but his First Venezuelan Republic ended in abject failure and Miranda would be handed over to the Spanish by Bolivar himself. Whether Miranda had betrayed the Revolution and thus Bolivar was acting rightly, or if Bolivar was a powerthirsty backstabber is still contended, but that's neither here nor there. Suffice it to say that Miranda's ideas profoundly influenced Bolivar and inspired him to dream of a Latin American confederation too.

The basis for Gran Colombia was first articulated in Bolivar's Letter from Jamaica, which he penned while exiled in, well, Jamaica. This letter is perhaps the greatest exposition of his ideology and the closest Bolivarianismo came to be a coherent political program. Here, Bolivar not only defended the struggle for independence as just and necessary, but he proposed ideals of Latin American union. Unlike Miranda, he didn't advocate for a single republic, but rather for cooperation between several independent, but closely linked, states. For the most part, these states would follow the borders of the old Viceroyalties. They would all meet in a Congress in Panama to secure friendship and cooperation. The Viceroyalty of New Granada would be one of the new nations, now called the Republic of Colombia - Gran Colombia is a term of historiography, used to differentiate it from modern Colombia.

Now, it's important to signal that due to the difficult terrain and a strong tradition of regionalism Spanish America formed a way less cohesive unit than, say, British America did. Consequently, even though the Captaincy General of Venezuela was in theory under the authority of the Viceroy at Santafe (Bogota), most of the time it ruled itself. Likewise with the Royal Audience of Quito. This helps explain why there was no "Continental Congress of New Granada" that declared independence as a sole political entity. Rather, Quito tried to declared independence on its own, and later New Granada and Venezuela also declared independence on their own. The result was that there was little help or unity of purpose between the different emerging nations.

Even within these subdivisions there was a lot of regionalism and struggles for power - New Granada, after declaring independence, entered a civil war known as the Patria Boba (Foolish Fatherland) characterized by the struggle between centralists and federalists, a theme that would define Latin American politics for the next century at least. In Venezuela, too, cities like Barcelona allied themselves with the Spanish because they didn't want to submit to Caracas. Thus, the initial phase of the independence wars was Granadinos fighting for an independent Granadino Republic and Venezuelans fighting for an independent Venezuelan Republic. Even Miranda, the idealogue of Latin American unity, fought only for Venezuelan independence. The idea of a Republic that united the entire Viceroyalty was simply not there, until Bolivar brought it forward in the Letter from Jamaica.

This gives Gran Colombia a slightly artificial quality, at least in some historians' eyes, for it was the result of Bolivar's will rather than the people's will. In any case, when Bolivar returned and called for a Congress to meet in Angostura. This Congress decreed that Venezuela and New Granada would now be forever united as a single republic "that shall bear the glorious name of Republic of Colombia" and then called for a Constitutional Congress to meet later and give a constitution to the new nation. While this happened, Bolivar managed to secure the perpetual independence of New Granada at the Battle of Boyaca in 1819, where Venezuelan troops fought side by side with Granadinos. This gave him the material resources and political advantage he needed to continue with the war, liberating Venezuela and securing its independence at the Battle of Carabobo in 1821. That year, a new Congress met in Cúcuta, drafting a constitution for Gran Colombia.

Though Bolivar claimed that he did not want power and that the representatives in both Congresses were free to enact whatever they wanted, they obviously followed the will of El Libertador. This resulted in a Centralist Constitution, where public power was concentrated in the central administration in Bogota. Local officers would be appointed by the Executive, and all laws would be passed by a national Congress. For Colombia to adopt such a centralized system was puzzling, since regionalism was still a strong force, most provinces and territories remained jealous of their rights, and distances and terrain made communication difficult. The answer is that Bolivar willed it, because he frankly believed that Spanish Americans weren't ready for popular government and that a strong, centralized administration was the only way to ensure their safety, independence and prosperity. This view was informed by the Patria Boba and the fall of the Second Venezuelan Republic, traumatic events that Bolivar blamed on weak governments and lack of cooperation. For him, democracy and federalism wasn't about liberty and autonomy, but anarchy and civil war.

The political, economic and social history of Gran Colombia is convoluted and hard to explain in a few paragraphs. The decade the Republic lasted was characterized by political strife, as Venezuela and other territories feuded with Bogota, and economic disaster, due to the war. Bolivar was not there, for he had left to continue the fight for independence in Peru. Vice-President Santander took charge during this time, increasing the political problems for he was a Granadino distrusted by the overwhelmingly Venezuelan military establishment, this even though Santander was a military man too. Santander was a capable administrator of a liberal stripe, and he and his men did their best to modernize Colombia and bring it into the ideals of 19th century liberal thought - equality under the law for all races, slave emancipation, free market economics, support for education, etc. Still, the Venezuelans were not happy. Though there were some who demanded independence, others would have been happy with a federal republic.

Ultimately, the man who started the process that would lead to Gran Colombia's disintegration was not so much guided by ideology as by hatred of Santander and a desire to protect the "pobres militares" from his supposedly evil designs. Jose Antonio Paez had been a firm patriot who rallied the llaneros, rough ranchers, to the cause of independence. He believed himself entitled to a greater part in the new Republic, and resented how he was confined to military, not political, command over Venezuela. When the Congress tried to impeach him, he raised the standard of rebellion. This was not an expressly pro-secession movement yet, since Bolivar had made it clear he wanted to preserve Gran Colombia. It was not clear what the movement wanted, in fact, since it was simply in favor of reforms and against Santander. Bolivar then returned and arranged a tense peace, but he praised Paez and did not punish him even though he was, for all intents and purposes, a traitor and a rebel. Santander pointed out, quite rightly, that if Paez and his conspirators were the saviors of Colombia, then he and Congress were criminals. Bolivar's actions did much to weaken and demoralize constitutionalist sentiment in Venezuela and streghten the men who formed the pro-secession movement "La Cosiata".

There's already a great answer by u/Red_Galiray covering most of the question - I wanted to add some more on the background, adapted from an earlier answer. This is to show that while Bolívar was completely central to the wars of independence, both he and those wars built on longer developments and precursors. So that the failure of his own plans was arguably overshadowed by the effects of the wars.

Precursors to independence

In contrast to the wide-spread Bolívar myth (highlighting solely the „liberator's“ importance), it should be highlighted that Bolívar and his collaborators built on the work of various precursors and teachers. These constitute examples of attempts at implementing European and Northern American models of governance in Spanish America already at the turn of the century. However, the later wars of independence profited from political upheavals in Spain and South America. My focus in this part will be on the late 18th an very ealry 19th c.

Precursors:
Limited Indian revolts took place in response to the burdens of tribute and forced labor quotas, especially in connection with the repartamiento system. Political revolts included one known after its leaders as the Tres Antonios in Chile (1780) – it called for one of the most democratic agendas at the time.

Social rebellions took place as well: More than 60 such revolts started in the 1770s alone in the Andes. However, they rarely moved beyond their place of origin and did not plan to topple the colonial regimes. A more extreme case was the famous rebellion of Túpac Amaru II that began in 1780. It had serious social overtones as Túpac had been radicalized by the system of forced labor and forced sale of goods to Indians, as well as by tax increases. The fact that indigenous people and members of other (non-Spanish) castas fought on the rebel's side might have alarmed creoles that a war against the Spanish might unleash an indigenous uprising.

Another form of revolt was civil protest. The independence movement can be seen as a direct result of the logic and method (if not the demands) of these protests. They sometimes escalated into open revolt as well, and were founded on traditional Spanish political theory: That is the elite's belief in virtual rather than actual representation, in that they were governing on behalf of society. Examples of civil protest include the Quito rebellion and the rising of the comuneros (near Bogota), which had creole, mestizo and indigenous participation.

„Teachers“:
Teachers is not the perfect term here, I'm looking at earlier thinkers who influenced Bolívar and others. One famous example, Simón Rodríguez, was actually Bolívars childhood teacher though, and participated in his independence campaigns as an educator. Rodriguez' influence on Bolívar is hard to gauge, as they held increasingly divergent opinions in Bolívar's later life. Rodríguez had a more radical (/ambitious) plan than most of his contemporaries – he advocated for a Spanish American social revolution to accompany the military revolution.

According to him, the education of a generation of students would create a democratic society from the ground up. This was quite different from the 'top-down'-approach taken by most leaders in the post-independance period. He looked to typographic innovations as attempts to circumvent the divisions between lettered oral culture, allowing not-learned readers a clearer approach to his arguments. Rodríguez was a strong proponent of American originality: According to Ronald Briggs he “had seen the fruits of Enlightenment and found them wanting”. Thus in his teachings he took into account the poor and orphaned; and called for a transcendence of racial identity through the elevation of mestizaje - both uncommon arguments at the time to say the least (Rodríguez is a pretty fascinating figure). Lastly, he wanted to learn from European political mistakes and copy the successes.

Another interesting precursor was Francisco de Miranda. He had a grand design for Spanish America as an autonomous, monarchical empire. In 1806 Miranda attempted a failed invasion at Coro, Venezuela. In the following he sent word from London to Venezuela's Creoles to assume control of the provinces (in mid 1808) – Caracas' first autonomous junta was formed in 1810.

As a dictator during Venezuela's short-lived first independence Miranda held plans for a Pan American Union (not that dissimiliar from Bolívar's later plans). Bolívar at that point shared much of Miranda's perspective: Both were in favor of British support, the British political model, perceived the American Continent as a whole, and both saw the importance of public relations with England and Europe; although it should be added that Bolívar was already more pragmatic than Miranda and saw him as idealistic. Nonetheless, I tried to show two major influences on Bolívar's later policies with Rodríguez' and Miranda's influence. And more generally that there were many precursors to the independence movement, not only in earlier leaders (there were many more of course), but also regarding earlier revolts and forms of protest.

One development still to be highlighted regarding the wars are the siginificant upheavals in the early 19th c. which influenced the independence movements' ultimate successes, and aided them in comparison to their precursors. Upheavals include the Seven Years' War and Napoleons' invasion of Spain and capture of its monarch; and the Spanish prince/later king Ferdinand resorting to coercive measures (sending armies) to squeeze revenues from merchants around the empire. This meant that the old loyalist coalition, held together with the promise of a measure of home-rule and regal loyalism, was smashed and that the new coalition, of which many had preferred home-rule in empire, opted for secession.

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