I suppose he fancied that, if Virginie never saw or heard more of him, her imagination would not dwell on his simple disappearance, as it would do if she knew what he was suffering for her sake.
"At any rate, Pierre saw that his cousin was deeply mortified by the whole tenor of his behaviour during their walk home.

When they arrived at Madame Babette's, Virginie fell fainting on the floor; her strength had but just sufficed for this exertion of reaching the shelter of the house.

Her first sign of restoring consciousness consisted in avoidance of Morin.

He had been most assiduous in his efforts to bring her round; quite tender in his way, Pierre said; and this marked, instinctive repugnance to him evidently gave him extreme pain.

I suppose Frenchmen are more demonstrative than we are; for Pierre declared that he saw his cousin's eyes fill with tears, as she shrank away from his touch, if he tried to arrange the shawl they had laid under her head like a pillow, or as she shut her eyes when he passed before her.