Veronique Rousseau has a serious and hard outlook on life unlike her brother Jules. Though despite her cold demeanor, she would consistently warm to Sean Devlin. Their friendship was smoldered nearly irreparably when Jules was killed on a trip with Sean she insisted they don't go on. As the game goes on, Veronique shows her firm distaste for Sean afterwards, but finds a new spark for Luc Gaudin, the man leading the French Resistance at the time. This pained Sean heavily, not having forgiveness and Veronique showing romantic interest in someone else, as he is in no place to change her feelings. Veronique's life is redefined as she finds her new goal, to serve and liberate the people of France. This also gets between Sean and Veronique as Luc is inspired to help the people by his love of Paris, as is Veronique, while Sean is only inspired by revenge. While Veronique supported the work that Sean did for the Resistance and assisted him, and even went on missions that were dependent on Sean, she still despised his reasons. She also missed her brother but realized that Sean's plot to kill Kurt Dierker would never help her with her lost brother, and wouldn't help Sean with his lost friend. Though this was problematic, and drew her closer to Luc, Veronique's biggest responsibility was that to Paris, and refused to allow romance to interfere with her goals.
Later, when The Resistance is ratted out by Santos and the Nazi's are alerted to their hideouts, Luc is trapped while Sean and Veronique had to leave. Instead of leaving him there, sure to be caught by the Nazi's and tortured until he gave information, Luc demanded Sean kill him before they got the chance. Sean could not do so, and Veronique took the gun and shot Luc herself. This also shows that despite her relationships, nothing is more important to her than The Resistance.
Eventually, when Sean gets his chance to get his revenge, finally, just before Sean confronts Kurt Dierker on the Effiel Tower, they kissed. It is implied from this point on that Sean and Veronique would continue The Resistance themselves.