Although Isabelle wants to show Vianne that she cares about her, the constraints of war and the resistance movement have made this kind of love impossible. When Isabelle asks her resistance friends to look after Vianne, they remind Isabelle that her participation in the resistance comes at the risk of her loved ones. Later, when Isabelle intentionally lies to Vianne in order to explain her departure for Paris, she is saddened when Vianne believes her selfish story. Yet in order to help people like her sister by working for the resistance, Isabelle must allow her sister to continue thinking that she is selfish and doesn’t really love Vianne or Sophie. For Isabelle, the inability to outwardly show her love is the cost of war.