Falling in love is exhilarating. It can also be a bit scary, especially when a home has captured your heart. What if something goes wrong and you end up not spending the rest of your life with this stack of brick and mortar you're lusting after? No matter how careful you are, some deal killers are unavoidable. Others, however, are preventable, so pay heed if you hope to keep your deal alive. 1. Don't Mess with Your Mortgage Prea…