Maybe I'm having a senior moment, but try as I can, I'm unable to come up with reasons why a person's marital status is relevant information on most forms.
I wear a wedding ring, as does DH - that is our choice. Anyone who meets me, a sales assistant who serves me for example (or even someone who sits next to me on the bus) will know I'm married. I refer to "my husband" in conversation as well. But why, when we are filling out 99% of forms, do any of us, male or female NEED to declare our marital status?
I can see why if claiming means-tested benefits, or for medical purposes ("does this person live alone, or do they have someone at home who can care for them?") but why does a random company need to know when I sign up for an online account with them? Or any of the other gazillions of examples. Why do these organisations need to know whether we are potentially available as sexual partners? I really can't think of any other logical reason why they are asking! 