What is Marji’s reaction to the break-up?

Seeing that the letters are in Marjane’s handwriting, Mr. Satrapi asks his daughter why she had not told him of the situation. He explained that Mehri’s love is impossible because “in this country you must stay within your own social class.” Disgusted with this answer, Marjane goes to Mehri and tells her that the next day they will go and march with the demonstrators.