It means a girl who is their for you, she knows when the right time to say something to help you. She gives you the shoulder to cry on when you need it the most. If you ever have a Marian street in your life your lucky. I am sure she would be a very long-suffering wife
Friend:”did you see That girl earlier?”
You:No?
Friend: She is such a Marian Street..
You: what do you mean Marian Street?
Friend: Marian Street means she is so kind hearted and sweet.