Trusting her with a book of spells, With all the knowledge of destruction for yourself, Teaching her each and every incantation, Letting her be to practice it all. Even if there's no certainty that she won't use it on you, But you are willing to bear the pain if that is what she wants, Because you know you are willing to give your entire soul to her.
Now that's a great sacrifice for someone. To be able to give your all to the person you truly care.