My purpose for living.

Today my friend told me about her day.
How she broke up with her boyfriend that was 5 years older then her.
I told her that she shouldn't go out with an 18 year old in college, that you haven't even met.
They were in a long distance relationship. Which made matters worse.
When your so young and they're so old, and you don't know them, you cant take them seriously.
I tried consoling her and telling her should go out with people closer to her age. Also she shouldn't be so hung up about this guy she doesn't know. She's much to young to be facing these types of difficulties in her life.
I told her my idea of how she should think about it. How people don't take you seriously at a young age.
Her reply was simply, "Just shut up, you don't know anything."
I understand she was sad and depressed, but taking these matters out on people who just try to get other people to feel better really made me mad.
Even with my anger I simply said I was sorry and explained I was only trying to help.
She hasn't replied....
It made me think my purpose in life was to take other peoples sadness. To just steal it away so they could be happy, but I would suffer. With my anger all I could think was, I hope she feels better, and that she'll still be my friend. I really do want that to be my purpose in life.