k.d. lang is done with longtime girlfriend Jamie Price -- k.d. has filed legal docs to dissolve their domestic partnership.

According to the docs, the couple registered for a domestic partnership in 2009 -- and separated 1 year and 9 months later ... in August 2011.

The pair hooked up in 2003 after meeting through a Buddhist teacher.

FYI ... a domestic partnership creates community property rights in a relationship, along with spousal support. It also allows each party to make health care decisions for the other. And for same-sex criminals, it gives the non-offending partner jail visits.