Definitions for "Boston Marriage"
refers to a type of romantic friendship practiced by American 19th-century feminists; these romantic friends moved in together long-term and aided each other in political activism and household tasks.  Straight women as well as “lesbians” engaged in Boston marriage; sexuality was not considered to be part of the relationship, although some closeted lesbians probably did call their relationships Boston marriages.
The nineteenth-century term used to describe two women who shared a household in a marriagelike arrangement. Women involved in "Boston marriages" lived independently of men and drew emotional and material support from one another. It is not clear whether all or most "Boston marriages" involved sexual relationships--some probably did and others probably did not. In any case, couples like Sarah Orne Jewett and Annie Fields certainly found important companionship and support in their intense bond with one another.
In the late nineteenth century, it was common for two unmarried women to share a home. Many women, particularly those who were college educated, lived in long-term unions with other women. These relationships became known as "Boston Marriages." These relationships offered women of a certain class a socially acceptable alternative to a traditional marriage. Certainly some of these relationships had a sexual component, but it cannot be known how many. Today these women would have been called Lesbians, but the term was not coined until 1890.