Yes, I do agree that in some circumstances that "Ignorance is Bliss." This relates to Faustus because at the end of the story he knows exactly when he will die, and he becomes scared of the inevitable. He wants to repent but he has already gained the knowledge so there is no going back. The knowledge he gains he is not able to handle the thought of it all. If Faustus were to never know and be "Ignorant" he would be more at peace. Bliss in this phrase can mean serenity and peacefulness. Ignorance is bliss is true in Faustus's case.