How are Stella, Stanley, Blanche, Eunice, and Steve interrelated in A Streetcar Named Desire?

Stella
and Stanley are married. Eunice and
Steve are married. This makes Blanche seem all the more the
solitary and
needy outsider. Eunice and Steve are friends and neighbors of Stella and
Stanley.
There are only two flats in this small building, upstairs and down.
Eunice and Steve live
upstairs. They are lower-class types like Stanley. All
three of these characters are vulgar but
honest and strong. Stanley and Steve
are poker-playing and drinking buddies. Stella and Eunice
are girlfriends who
share their troubles with each other. Stella, like Blanche, comes from the

upper-class Southern world represented by their...