At the end of their day together, clearly Edna is falling in love, evidenced by her silent evaluation of Robert's voice as "not pretentious" but "musical and true" — as if she is comparing his voice to Léonce's more formal, pretentious personality.
Note that Etienne could not be soothed by Madame Ratignolle, the epitome of mother-women, but needed his mother's presence before he could be soothed to sleep. While Edna may not be the model mother in her husband's eyes, still her children have a necessary attachment that is unique to her. When at the end of the novel she considers the impact that her behavior will have on her children, this strong bond is uppermost in her mind.
