Paul's mother is very selfish and hungry for money.  Her love for her husband turned to dust for several reasons.  Since he brought in a small income, he is never able to fulfill his wife's yearning for money.  Even worse, he is not a lucky man in his wife's opinion, and the only way to keep money coming in is to be lucky.  Finally, she associates him with her children, and she has no warm feelings or maternal tendencies toward them. 

Being unlucky is usually a perception of a situation; in this case, Paul's mother's doesn't feel she has enough money in spite of the fact she appears to have a middle class, if not above, dwelling, all the necessary material possessions, and household help.  Her true unluckiness lies in her inability to be satisfied with with her life, which results in unhappiness and dissatisfaction.