Society makes nothing but trouble for the characters in Howards End. The notion that each of us is socially predestined for a certain kind of life based on who our parents are and how much money we have (or don't have) is incredibly frustrating to accept, but in England in 1910 it's an unavoidable fact of life. Definition by class is an obstacle that all of the characters in Forster's novel face, and it's one that challenges what really matters, individual human relationships.
Forster makes problematic the very concept of social class itself by revealing a society torn between two competing systems of hierarchy, those of liberalism and imperialism.
The end of the novel proposes a possibility of a utopian future for England, which can only be attained by the breakdown of social class.