Edward VIII was King of the UK, however he abdicated because he wanted to marry a divorced woman.
Someone told me that the "real reason" was that he was trying to influence the UK government and/or civil service. The various organs of the UK government are all nominally "His Majesty's Something-or-other", so it's a tricky situation if the monarch tries to interfere. However, in practice, the monarch has no real power. The rumour is that he was pushed out by the government due to this interference. I've heard that the current Prince of Wales (Prince Charles), has likewise tried to influence the government, e.g. in favour of homeopaths, etc.