Need to see a psychiatrist. A disorder?

My sister is a teacher. She is happy in her life) with husband & two sons. They are living in a joint family (inlaws of my sister) my brother in law lives in delhi due to his job and my sister lives in bhopal. she have some problems in her family (with her mother inlaw). Due to this she s going through depression, though she is good and i dont see any phychiatric problem in her behaviour since years. But recently some musunderstanding started between my sister and brother in law. Its now a bit serious and its reported( by my brother in law) that my sister calls him at around 12:00 am and asks him abt the mishappenings in life. There is a lot more. At present my looking for an advice as whether she needs a psychiactric treatment/ is it a disorder?? Plz advise