Actually it was the UK that advocated the expansion east. the EU does not want to expand further - it’s rejecting even Serbia and other Balkan states accession.
For the time being.... and please make a distinction between what our corrupt, europhile ruling class wanted and what the British people wanted. Britain’s Europhiles are their heirs to the old Empire’s ruling caste who think it is their place to rule the world and have never given a damn about the ordinary Britons they consider barely above the level of livestock in terms of respect and standing.