The UK never quite came to terms with the end of its empire. Once the Brits joined the EU, they latched onto Europe for everything they needed and skipped over the transition that all the other imperial powers went through. So, they were already outdated, but had a crutch to rely on; then Brexit hit and it left the UK stumbling and fumbling.
With the UK’s future up in the air, there’s really only two paths forward. First, they could seek out new trade deals globally, but they’ll have to find some new non-imperialistic tactics to do so. Second, they could swallow their pride and nestle up under the Americans’ wings.