As an elder brother, I would tell her that she has experienced something that she will have to go through a lot in life. Not just in matters of love but in many other things.
Heartbreak is not limited to your love life, but also to many other things. Sometimes you won’t be able to get into the college that you wanted to get admission into, you might not be able to get as much marks as you hoped you would get even though you poured your heart into studies, you might not be as adored by friends as you thought you would be, college might not be as fun as it is portrayed in the movie etc. The list is endless.
Life is not always in black and white. The grey shades are more to be found than any other. Learn to bounce back and utilise your energy productively. There is a long way to go from 17.