"Edward VIII abdicated because it would be an abomination if an American divorcee was the wife of the King"

That's the cover story. Now that many alive then are deceased, more facts are coming to the surface. She was highly pro-nazi (as indeed many Rich Americans were at the time - there was a strong US Nazi party till Pearl Harbour and Hitler declared War on the USA a few days after) - great personal friends with many high ranking nazis, and Edward was very amenable to them as well. Many such as Churchill were adamant that if he remained as King, Britain would become officially pro nazi too.

Some of this is covered in, and highly relevant to the recent movie "The Kings Speech". Documented too.