I have been married for 5 years, together for 15. My wife and I have a mortgage on a block of land. Now she tells me she doesn't want to build on it. I'm determined to build on the block. She also is not ready for kids - I'm super keen now. Do I make a clean break and pay her for half of what the block is worth (minus what's outstanding on the mortgage), or is there a way to get her to sign something so that the whole building project is mine and she can't claim half of it later down the track if we do decide to go our own way?