I think that they've all failed each other in a number of ways. The article for the short excerpt below can be linked at the bottom of the page.
"In A Raisin in the Sun, Walter’s desire for wealth obviously surpasses his family members. In many parts Mama criticizes Walter’s dissatisfaction with his life. Ruth is also openly critical of Walter’s clamoring for money, however, secretly negotiates with Mama trying to persuade her to give Walter a chance by granting him a portion of the life insurance money in order to start a liquor store—hinting to a commonality of grievances. For example, Beneatha exclaims that George ( a wealthy boy that seeks to court her) is “shallow”, and Ruth inquires as to “what other qualities a man got to have to satisfy” her. This implies, therefore, that Ruth identifies wealth as a vital characteristic. Even Mama, who most vociferously proclaims contentedness, dreams of a new house and understands that only money will provide the way for such a transition. Moreover, as her main goal to become a doctor mandates that she have money, Beneatha relates to the familial ilk of materialism as well. Either plainly or subtly, all members of the Younger family are discontent. Their discontentedness leads to disunity, mutual animosity, and ultimately failure. Their failure to remain collected, failure to overcome in the midst of adversity, and failure to be content under the most disheartening circumstances reveals their lack of intestinal fortitude. The Younger’s deviate from success not because they fail to fulfill all their dreams, but because in pursuit of their dreams they lose sight of what really matters—family. The Youngers individualistic mentality and lack of humility, especially Walter’s, grows violently. This characteristic disposes of morality in favor of personal goals and aspirations. Walter’s liquor store is one example. Later the Youngers reestablish themselves by demanding Linder, a racist neighborhood manager, “get out”. However because this was more a result of pride than justice, it may be poor evidence of the Youngers’ character. All in all, with the acute frustrations associated with a most terrible economic environment for African Americans and the financial hoi polloi, the Youngers fail to resist depression (although their circumstances allow for nothing else), and while they eventually gain a house the means of their acquisition portray them as undeserving."
