Early Census results showed an increase in the number of couples who cohabit. We know from history, though, that unmarried partners have to protect their assets just as carefully as married couples do. And while the issues may not be the same, the result of not planning for the break-up contingency can be painful, expensive litigation. The law doesn't provide for partners in heterosexual or same-sex relationships the way it provides for spouses or civil partners. So, what's an unmarried, cohabiting couple to do?