I would write many letters. Daily if possible. And I do not think it inadvisable to let her know, frankly and before she leaves, that you have these fears of losing her. Perhaps she's impressionable. The giving of affection and the determination to provide comfort are the two practicable elements of love.
Love requires no proof.
Seen in this light, love is a sort of faith, since a faith that required proof wouldn't be a faith at all. I'm gonna shoot myself. That's pretty stupid, Walter. You're not gonna shoot anyone. Maybe I oughta shoot you.