How impairing? Situational depression is as "real" as other forms of depression--it just has a known cause, as opposed to endogenous depression. Both can cause severe impairment. If one can change the "situation, " that may be the best treatment for the former. Medications can be helpful with either, as can several types of talk therapy. Doing nothing is the least helpful option.
Can't say. Without an evaluation. Make an appointment with a therapist or a psychiatrist.