It's probably a subset of (1), but an unexpected external event might be a good reason. If you're negotiating for a new house for your gran and she loses an argument with a car, suddenly you don't need the house any more. There's an implicit assumption that she'd be around to need the house to which both sides may have been party. Perhaps an aeroplane crashed into it and destroyed it, so although gran is still alive, there's now no longer a house to buy.
no subject
Date: 2012-03-29 06:14 pm (UTC)D