This reminds me of something I heard on the radio years ago. This solicitor was talking about people who were not married coming to him for advice on house purchase. He always said, "and what is going to happen to the house if you split up?" and they always said, "no, we are never going to split up", and the majority turned up a year or more later with, "we're splitting up, what shall we do about the house". Seems like it is something that nobody wants to work out in the cold light of day before the event. Sorry if that does not help your quandary, but was this never discussed before joint purchase?