It's very similar to marital status. However, marital status should only elicit the answers "married, single, widowed, divorced".
Relationship status can be "single; dating; in a relationship; co-habiting; married; separated; divorced". I would not give "widowed" as a relationship status.
If you are a member of Facebook, you will know that one of the "Relationship Status" choices is "It's complicated"!
Student or Learner