I'm not really qualified to say why it ended up happening, but I think can talk about the more long term consequences of Suez for Britain.

The most important thing to recognise about Suez, from a British perspective at least, is that it was not a particularly major blow to the special relationship, nor was it as great a surprise as is sometimes assumed. Despite undermining the British during the Crisis, American diplomats did not seek to swear off cooperation with the British, as they remained a figure of great influence and experience within the region. A fairly clear example of this is that by 1957 Eisenhower and Macmillan were already engaged in discussions that the former would characterise as 'the most successful international 14 conference that I had attended since the end of World War II.' More concretely, the US supported the British regarding the Baghdad Pact, antagonising Nasser, indicating some level of loyalty between the two nations.

As for Suez being a sort of watershed moment for British politicians, where the realised the sorry state of themselves in the world, such statements are an overstatement. Various government papers, such as 'The future of the United Kingdom in world affairs' in 1956 indicate that Civil Servants and ministers recognised a need to toe the line set by the USA, and that it no longer could afford to intervene directly to the extent it once had. Eden's decision was thus contrary to prevailing wisdom, and this is reflected in the fact that numerous figures in the Ministry of Defence, Foreign Office, and Labour Party were outraged by his decision, and his attempts to keep the decision making process in the hands of a small few.

We can thus say that while Suez was very much a blow to international prestige, and destroyed Eden's premiership, in terms of ramifications it wasn't really a massive lesson for British diplomats, nor did it affect the relationship long term.

Apologies if this is not a good enough response, any feedback would be appreciated.

Sources:

G.C. Peden, ‘Suez and Britain’s Decline as a World Power’, The Historical Journal, 55(4) (2012), 1073-1096.

Scott Lucas and Ray Takeyh, ‘Alliance and Balance: The Anglo–American Relationship and Egyptian Nationalism, 1950-57’, Diplomacy and Statecraft, 7(3) (1996), 631-51.

David Reynolds, Britannia Overuled (Abingdon: Routledge, 2013).