Ill health ~ both physical and financial
Right, bad luck, c'est la vie. 
Note to self: Avoid making comments which, at a stretch, could be taken seriously.
Now don't be like that ~ It was a sensible question that everyone asks ... probably because we all have, at one time or another, thought that we would like to run a country pub. I give all enquirers the same answer which happens to be true. "Ill health etc"
I recall one Saturday Night when the pub was going like a train. It was Carnival night and the parade started at 7.30 from the field next to my pub. Money was being passed overhead from people in the street via the open windows and pints passed back. Being sensible I had laid in a stock of plastic glasses. Hate the things but it was necessary for that one night. In 2 hours we pulled over 2000 pints. It was manic. Finally the parade moved off and the bulk of the customers followed. I pulled myself a pint, gave all the staff a drink and sank into a chair. My elder (and at the time only) daughter, who was visiting, came into the bar and seeing me recumbent said "I bet you are glad you gave up work to do this". If I had found the strength she would not have survived.

Then two heart attacks in two years, the Government wrecked the Tenanted trade by forcing the Breweries to sell off their pubs and we bailed out. No money in it and no life working 90 hours a week.