According to the USA government (most likely all state governments too), unless you're married, separated, divorced, or widowed, you're legally single. I only say this based on all forms and applications related to the governments. It's funny. Every damn time I fill something out I question it and sometimes I smile.
nebula:
I always find it weird too. Likewise when I have to fill emergency contact info out on anything and the only options are to list a family member or a friend. Probably a telling way to figure out how people feel about their significant others haha