Voltaire once said: Doubt was unpleasant, but unquestioning certainty was absurd.
Women were like that. Their hearts could only love one person at a time. When their hearts belonged entirely to their husbands, their sons became secondary; when their hearts belonged entirely to their sons, their husbands had to come second.
Both Narcissa Malfoy and Lily Potter put their children first. For them, they could give everything they had, even their lives.
This was indeed the maternal love people praised, but it was also a woman's psychology: she wanted to leave the very best of everything for him.
People in Roman times were not like that. If a son was not strong enough, he would be thrown into an infant-exposure ground. Their affections leaned more toward their husbands. As Medea sang in the play, women of that era regarded love as more important than life itself, never caring about the disasters and hardships about to descend upon them. Thus, when Medea learned that Jason had betrayed her, the princess who had once considered Jason in everything suddenly became Nemesis, killing Jason's heir and his new lover alike.
Likewise, if a woman did not have that man in her heart, she lacked concern and affection for him. She would only draw from him instead of giving for him, and she would always calculate her own gains and losses.
Run off with Tobias Snape to live in a slum like Eileen Prince? How could that be possible? A woman like Josephine could move through high society for the sake of her two children, or she could use them as an excuse to deceive an emotionally innocent young man into marrying her and helping her pay off her debts.
Men sometimes could not see women clearly. What sort of women had a man