This was generally not a war of cultures since American and British citizenry were extremely similar. It was (very simplistically) an issue of taxation and representation. During the 7 Years War, also known as the French and Indian War, Britain spent a large sum on protecting and defending its colonies throughout America from the French. This war was a massive drain on the British economy and to help recover they decided to tax the American colonies more heavily than before since much of that expense had come specifically from defending the colonies themselves.

Even after the war there were substantial factions on both sides who assumed the two would be reunited again eventually due to the cultures and citizens being essentially one and the same. This is all of course a very simplistic explanation and of there are tons of nuances on each side.