One short story that deals with these issues is "Everything That Rises Must Converge". A novel dealing with these issues is Go Tell It On the Moutain by James Baldwin, and another is A Place To Come To by Robert Penn Warren.
Datnebnnii - I would put this in a discussion post because you could probably get more responses. However, you could easily use the classic novel Gone With the Wind which deals with class issues before and during the war. Scarlett, the main character, also struggles with her role as mother. There definitely are various love triangles in the novel as well.
Other books I can think of would be:
The Pact by Jodi Picoult (deals with romance and parenting)
Sing You Home by Jodi Picoult (also deals with romance and parenting)
The Great Gatsby (deals with topics of wealth vs. poverty and romance)
Water for Elephants (poverty & romance)
The Book Thief (although set during the Holocaust and has many themes of racial prejudice, it does also deal with money issues and parenting)
The Hunger Games by Suzanne Collins (parenting somewhat, romance definitely, poverty definitely)
Love Medicine by Louise Erdrich (all three)
I tried to give you a variety of genres and levels of reading. Good luck! Again, posting this as a question in discussion may yield you more results.