Melissa and Tammy Etheridge have separated.
"We ask for consideration and respect for our family as we go through this difficult period," the pair said in a statement.
The couple had been together for almost nine years. Melissa, 48, and Tammy, 35, held a commitment ceremony in 2003. They had planned to legally marry in 2008, but missed the chance when Proposition 8 passed.
It is not known if Tammy Etheridge will reclaim her former name, Tammy Lynn Michaels. In 2006, she gave birth to twins, a girl named Johnnie Rose and a boy named Miller. The twins were conceived through an anonymous sperm donor.
Melissa Etheridge has two children with former partner Julie Cypher: a girl named Bailey, 13, and a boy named Beckett, 11. Both were fathered by rocker David Crosby.