Lillith,
I believe you are looking for the term "Boston Marriage" which was an more intense form of a romantic friendship. By the way, you should read Victorian New England writer, Sarah Orne Jewette, because she wrote a lot about women in "Boston Marriages." However, I would like to say that Boston Marriages were still taking place until the 1930s. Another writer highlighting Boston Marriages was Angelina Weld Grimké. Her heartbreaking work "Rachel" features an African American Middle class Bisexual woman who decided to live in Boston Marriage despite wanting children and a husband in 1915. This is because Rachel believes that by refusing to reproduce, she declines to provide her local Klansmen with black children who can be tormented with racist atrocities. This work is heartbreaking because it shows the character as well as the author longing for both man and female companionship. Plus, the racial/sexist elements can be very heartbreaking at times. Yet, Grimké shows a warm and loving romantic friendship between two middle class African-American women in 1915.
Here is this website about boston marriages:
http://www.glbtq.com/social-sciences/boston_marriages.html