There were a lot of hostilities between the UK and America in the interwar years that are comparable to China-US relations now. The British Empire was in decline, America was in ascendancy as the global power. America had just refused to join the League of Nations, which stoked suspicion and some breakdown of diplomacy. The American public was against British rule in India and some were against British control of Ireland. There were a lot of back and forth trade wars, then a few incidents of the two getting mad at the other's naval routes. There was a brief UK-America arms race in the early 1920s to build bigger and higher capacity battleships, until the Washington Naval Treaty was signed in 1922 to limit battleship size and armaments.

The British Empire didn't renew the treaty in 1932, and by 1933 it was fairly common understanding the UK might ally with Nazi Germany. The British weren't exactly...shy about praising fascism at first. There were a number of prominent British fascists, like Oswald Mosley and Harold Harmsworth (founder of the Daily Mail). Churchill himself made speeches praising Mussolini. So that made the international situation shaky.

So a lot of those conflicts were still unresolved by WW2, especially the American public expressing weird levels of sympathy for India and the Quit India movement. I guess there was some kind of feeling of camaraderie there, since America had also been a British colony at one point. Who knows.