if she shared razor blades then she would be at a higher risk then probably most other things living with someone HCV infected.
By sharing cigarettes? No; people can generally share sex without contracting Hep C. It’s spread primarily by sharing IV needles; it’s a blood to blood disease. Many of us in here have been infected and married for many years while our partners remain negative. It’s possible through sex; not likely. Sharing smokes; not hardly :o).
Take care,
Bill