When you use “Mr.” you are referring to a man, but the word does not reveal his marital status. The title “Ms.” (originally without a period because it was not an abbreviation of another word) was coined in the 1960s to be the female equivalent of “Mr.” Until then, women were referred to as “Mrs.” if they were married, widowed or divorced, or “Miss” if they were unmarried females of any age. Why should women have to let you know their marital status? It’s irrelevant.
If, however, a woman lets you know she prefers to be called “Miss” or “Mrs.,” do her that courtesy.